The best known (and perhaps most mature) of all live Linux distributions is Knoppix from Klaus Knopper.

Knoppix gained rapid attention when introduced because it actually worked. The theory of using read-only media and a Ramdisk to run Linux is easy enough to grasp, but Knoppix went a step further with powerful hardware detection and automatic configuration.

Knoppix stumbled on our test machine with the nForce motherboard chipset, but booted fine on other systems, dropping into the crisp Knoppix-themed KDE 3.1 desktop.

About 2GB of software is crammed into the 700MB Knoppix image, and decompressed on the fly as required. It's impressive and makes for a fully featured working environment. Everything from the boot loader to the desktop is cleanly presented.

The default desktop environment is KDE, and both KOffice and OpenOffice are included for office work, and Konqueror and Mozilla for web browsing. Other software ranges from the MySQL database platform, including server, and a digital planetarium.

Documentation for users and would-be customisers is strong, with a well developed user community. Knoppix's Debian roots show through with the omission of some packages considered 'non-free' by the Debian GNU/Linux project, but overall it's a coherent distribution. The hardware detection isn't head and shoulders above the alternatives, but anyone considering a live Linux setup should take Knoppix for test drive.

Gnoppix 0.6.0-rc2
Despite the similar names, Gnoppix and Knoppix aren't part of the same project, although they come from the same evolutionary tree. Like Knoppix, Gnoppix is based on the Woody build of Debian GNU/Linux, but instead of KDE uses Gnome (and only Gnome) as its desktop environment.

Booting into Gnoppix is fairly quick and the hardware detection does a fair but not impressive job; our display defaulted to only 1,024 by 768 and, although the Ethernet adaptor was ostensibly detected and configured correctly, Mozilla couldn't connect to the internet. The version under test is prerelease, but other distributions did a better job of setting up.

The Gnoppix desktop environment is Gnome 2.4. OpenOffice is the only office suite provided, with Evolution 1.4 as the default mail client and Mozilla as web browser. Utilities are provided for setting up a persistent home directory. In addition to the staple items there's a wide range of utility software from the Debian archives.

Gnoppix is a mixed bag. The features and included software are good, but the packaging is rough around the edges. Other live distributions are cleaner and provide more options for desktop environments, browsers and office suites. However, if you're a big fan of Gnome and aren't dependent on totally automatic configuration, Gnoppix may be for you.

Morphix 0.4.1
A Knoppix descendant, Morphix offers a smaller download and a modular selection of applications. Variants are offered featuring Gnome, KDE or a Light option. The big selling point of Morphix is the ease with which you can roll your own setup. The user community is active and, in addition to documentation on how to customise your setup, the Morphix site includes links to many different specialist builds.

The Light GUI variant boots the quickest, although its startup is still slow compared with a stripped-down hard disk installation. The interface is a clean desktop with a launcher bar across the bottom of the screen.

Morphix KDE ships KDE 3.1 as its desktop environment and the KOffice suite. Morphix Gnome, on the other hand, goes for Gnome and OpenOffice. Otherwise the setup on each is similar, although the desktops themselves are distinct.

For gamers, the Morphix Gamer setup offers a neat out-of-box solution, with the lightweight IceWM desktop handling X-Windows duty, and a slew of games installed a couple of clicks away in the menu.

The documentation for Morphix makes it clear that the whole project is a work in progress, and shouldn't be considered a finished product. It is, though, under active development and we found it was well enough advanced for the enthusiast crowd, and nearly ready for prime time.

MandrakeMove
Originally the Mandrake distribution was Red Hat Linux compiled with optimisations for newer processors. It's since grown into a separate product and is now much more than just a souped-up clone of Red Hat, with MandrakeMove as the live variant.

MandrakeMove is available directly from MandrakeSoft. While it can be downloaded for free, users are asked to join the Mandrake Club or to go on to purchase a boxed copy. The boxed edition of Move is bundled at different price points with USB keys of varying sizes.

MandrakeMove boots directly into KDE 3.1. On our test systems the display auto configuration left us with a disappointingly low refresh rate. In a fashion similar to Linspire Live, the MandrakeMove desktop and menus are organised neatly along functional lines, rather than as a jumble of programs familiar only to experienced users. The office functions sit on top of Open Office 1.1, and the browser of choice is Konqueror.

System configuration is based on Mandrake's own Drak tool, which has a clunky interface in places but isn't unfriendly.

Overall, MandrakeMove is a quality distribution. While the hardware configuration could be stronger, the desktop environment is slick and compares well with Linspire Live.

SuSE Live
The live version of SuSE is specifically intended as a demonstration version of its regular counterpart. Accordingly, no customisation is available, and there are other ups and downs to this approach for the casual user.

First, SuSE Live takes a long time to boot. On boot the standard SuSE installer - YaST (Yet another Setup Tool) - kicks off to detect and configure hardware. While YaST does a superb job of setting up hardware, it takes a long time to do it, and the system proper does not boot up until YaST has completed its process.

These steps in the boot process itself (such as generating an SSH host key set) would normally be one-time operations for a hard disk install, but with a read-only system these are of course every-time operations.

Once the system has booted, though, things take a distinct turn for the better. A clean and well presented KDE 3.1 desktop has icons on the desktop for KDE's Konqueror browser and the Open Office suite. A well laid out menu and quick launch buttons in the KDE taskbar round out the polished feel.

The time waiting for YaST to complete is worth it; on our test system the resolution had automatically been set to a useable 1,280 by 1,024 with a refresh rate of 100Hz, and the network interface was properly determined and configured with DHCP. Mozilla is installed as well as Konqueror for those who prefer a different web browser.

SuSE Live hits its target market very well. It's not for the tweaker, and it takes a long time to boot. But it is polished, does a great job of detecting hardware and bundles a sensible suite of applications.

Mepis Linux beta 2
Until now Mepis has been a relatively unknown brand in the Linux world. As with many other distributions the standard offering is for a hard-disk based install, and the live version is a sideline. As sidelines go, though, this one has some interesting features.

On boot Mepis offers a GRUB-based menu of choices. Power users will appreciate the choices on offer, with different screen resolutions and different kernel versions. Once you choose an option the system starts up almost like a normal Linux box.

There's no pretty logo screen with progress bar, instead you can see the auto-detection routines doing their thing and subsystems initialising. This isn't as clean as some competitors, such as Knoppix (and its derivatives) or SuSE, but it works and is fine given the beta status of the release.

On our testbed Mepis had no trouble booting into a 1,280 by 1,024 KDE 3.1 desktop running on top of a 2.6.4 kernel. Both KOffice and OpenOffice are installed, as are Konqueror and Mozilla for web browsing.

Several Mepis custom utilities are provided for system management, including a hard disk installer that proved to be quick and flawless, installing a multiple kernel setup in just a few minutes.

The boot messages, look of the interface and overall packaging of Mepis aren't (yet) on a par with the better established or bigger name live distributions. But the feature set is good, and the distribution is up to date. For power users Mepis is already a good place to start, and it's getting better quickly.

Linspire Live
Formerly known as Lindows - the name was recently changed to avoid trademark issues - Linspire is targeted at the novice Linux user. Its live version is marketed mostly as a demonstration edition, but contains most of the functionality of the regular Linspire.

Getting Linspire direct from the manufacturer costs $30 (£17), but it can be downloaded from P2P services such as Kazaa and Bitorrent for free. This is permitted by Linspire because it saves the company the cost of supporting arbitrary numbers of huge ISO image downloads.

Right from boot Linspire (still branded 'Lindows') presents a clean interface that won't scare a novice user with in-depth descriptions of the boot sequence. Boot time is reasonable and once complete the user is dumped into a KDE-based desktop.

Unlike most other distributions the underpinnings aren't displayed up front. From the desktop itself through to the menus and the Internet Suite, everything is neatly branded as Lindows, which gives the environment a coherent feel.

The browser and mail client are both from Mozilla, and the (not rebranded) office suite is OpenOffice. Additional software is sparse but reasonable, and adequate for an office desktop.

Linspire Live is a cleanly presented distribution that shouldn't scare users new to Linux. It's not the most flexible or the most comprehensive option, but it's simple to use and covers the basics well.

LNX-BBC 2.1
LNX-BBC is a svelte distribution, at 50MB for the ISO image. The idea is that it will fit on a business-card sized CD-R so it can be conveniently carried around in a wallet. It's a similar idea to the Sysadmin Survival CD that Red Hat used to provide as part of its boxed Linux product. And, in a novel twist, if you join the Free Software Foundation your membership card will be a bootable CD containing LNX-BBC.

The space constraint of a 50MB image means that LNX-BBC has fewer features than the larger distributions. It's not intended as a drop-in replacement for a regular desktop Linux install but as a rescue CD for booting and inspecting systems.

Even here, though, LNX-BBC is conservative; the hard drives will be mounted read-only and you have to mount them manually to read/write to perform modifications. It's possible to roll your own variant of LNX-BBC using the GAR packaging system.

The current version of LNX-BBC is a little behind the curve, having been released in May 2003. That's not to say that this isn't a useful distribution, though. Plenty of tools are included for inspection and recovery of misbehaving systems, and the network facilities include SSH and Bitorrent clients.

LNX-BBC doesn't compete with the heavyweight distributions, but nor is it intended to do so. As a system recovery CD that fits in your wallet it can be forgotten about until you need it, and then it'll be a blessing.

Feather Linux 0.4.0
Continuing the 'small is beautiful' theme, Feather Linux demands just under 64MB. While it can be run from a CD, Feather is intended to run directly from a USB key drive. Unlike its big brother, Knoppix, you can run Feather from a USB key that doesn't cost almost as much as your PC.

Two variants are available: the standard Feather Linux and the Feather Linux Console Edition. The standard Feather aims to provide a small but useable desktop environment, including a surprisingly elegant and full featured window manager.

Space constraints mean that no office suite is included, but Feather does include music playback, administrative and network tools as part of the distribution, and tools to download additional software on a per-session basis.

The Console Edition is targeted at system administrators and is smaller still, requiring almost exactly 50MB. Very much along the same lines as LNX-BBC, the toolset is shaped towards diagnosing and repairing faulty Linux systems.

For most users Feather will be a compromise too far in terms of functionality. But for on-the-run system administrators Feather offers a neat and compact graphical environment along with a useful amount of power.

Conclusion
If you're new to Linux and considering a live distribution as an introduction without commitment, a handful of options stand out. Unsurprisingly it's the bigger distributions that offer the fewest surprises: SuSE Live, MandrakeMove and Linspire Live offer the friendliest interfaces as well as a good mix of tools.

• SuSE Live is the most impressive introduction, with only its slow boot time counting against it, but with excellent hardware detection and configuration, and a good desktop.
  
  
• Linspire Live goes far enough in branding that, in keeping with its Lindows heritage, it almost doesn't seem like Linux.
  
  
• Mepis is a promising distribution that doesn't quite yet match the established players for polish, but is advanced with its 2.6 kernel option.
  
  
• Mandrake doesn't match the SuSE hardware detection, but does have a polished desktop and applications bundle, and the option of a persistent home directory.
  
  

For the Linux enthusiast experimenting with live distributions the choice is a little different.

• The polish of SuSE Live won't compensate for its demonstration-focus and slow load time.
  
  
• The cosseted environment of Lindows isn't always the most comfortable for the long-time Linux user.
  
  
• MandrakeMove is the only big-name distribution that matches the polish of a solid desktop environment and application mix with the convenience of persistent home directory.

But for tinkerers there's a lot more fun to be had with the custom distributions.

• Knoppix shows its form as the longest-standing live distribution with wide-ranging documentation and a comprehensive set of included packages, packed into the 700MB of an 80-minute CD-R.
  
  
• Gnoppix isn't quite as comprehensive, but is the just the thing for big fans of Gnome (KDE is the prevalent default environment across live distributions).
  
  
• And perhaps most interesting of all is Morphix, with its modular system for building customised distributions including only what you need, all on top of a customised Knoppix.