The OQO model e2 is a portable computer that manages to squeeze a full PC specification into a handheld form factor. The device offers the equivalent power of an ultraportable laptop and is the best choice currently available for users seeking a full-blown Windows system they can carry in a jacket pocket.

Shipping in the UK since September, the model e2 is smaller than some portable games consoles, but runs Windows XP or Windows Vista. We found the device quite capable of running standard productivity applications, but some compromises have been made; its keyboard is not best suited to heavy text-entry work, and its small size limits its use to just a few hours on the standard battery pack.

Our review model was based on a 1.5GHz VIA C7M processor with a 60GB hard drive and running Windows XP. Other configurations include a 1.6GHz processor, hard drives up to 120GB, or a 32GB solid-state Flash disk. All models have 1GB of memory, Bluetooth and 802.11a/b/g Wi-Fi.

In tests using the Winstone 2004 benchmark suite, we found the OQO model e2 achieved a score of 10.4. This is comparable with the score from Samsung’s Q1 ultra-mobile PC (UMPC) released last year, but the model e2 feels more responsive than this result might suggest and more in line with ultra-portable laptops we have tested. Its low score can perhaps be attributed to the use of a tiny 1.8in Hitachi Travelstar hard drive.

We downloaded and installed the OpenOffice.org productivity suite, and found the model e2 perfectly adequate for editing and creating documents, even spreadsheets, ­ although the standard resolution of the screen cannot fit in as many cells as you would see on a desktop PC. We also tried various web-based applications such as Google Mail and IT Week’s own Web content management system, and found the model e2 handled these as ably as any other PC.

Although it packs the power of a laptop, the OQO has been designed to be used in a different way. It can be cradled comfortably in both hands, as you would a BlackBerry device, and you can then type using your thumbs. We found it easier to use like this than with the unit flat on a desktop.

Although small, the keyboard has special features to make typing easier. For example, the modifier keys such as Shift, Ctrl and Alt are “sticky”. Press Shift once, for example, and the next key you hit will appear in upper case. A small LED next to the key pulses on and off to show it is sticky, while pressing the same key again locks both it and the LED indicator on until pressed a third time.

The keys are small and rather calculator-like, and make it tricky to type at any great speed. The layout also takes a while to get used to, because some punctuation marks and functions are on different keys to a standard PC keyboard.

In place of a mouse, the model e2 has a track-stick pointing device fitted in the right hand-side of the keyboard, where it can easily be reached with a thumb. Two keys to the left of the keyboard serve as left and right mouse buttons. We quickly got used to this arrangement, but left-handed users will be at a disadvantage. There are also two touch-sensitive strips alongside the screen bezel that let you scroll up and down or horizontally by swiping the appropriate strip with your thumb.

The screen of the OQO model e2 measures 5in across the diagonal and slides up to reveal the keyboard. When closed up, the device looks like a miniature Tablet PC, and the model e2 does in fact support full Tablet functionality if users purchase an optional digital active stylus. The screen is left exposed, however, which could possibly lead to it being damaged, unless one of OQO’s carry cases is purchased.

Its display has a native resolution of 800 x 480 pixels, and we found it surprisingly easy to read. One potential pitfall with non-standard resolution displays is that dialog boxes can extend below the visible area of the screen, preventing the user from easily clicking any buttons there - we experienced just this problem with Sony’s Vaio UX UMPC earlier this year. The OQO gets around this problem by providing zoom in/out hotkeys that dynamically change the resolution, allowing you to make text bigger or step up to a larger resolution if something does not fit on the screen.

All of the OQO’s ports are located on the bottom edge of the case, and consist of an audio jack socket, a HDMI interface, docking connector, and a single USB port. The docking port is used to connect OQO’s mains power adapter. A small dongle supplied with the system also fits this port and provides an Ethernet connector and VGA monitor port, enabling the model e2 to link up to an external monitor or a projector for giving presentations.

A full docking station is an optional purchase, and provides video and Ethernet ports, can connect to a desktop keyboard and mouse, plus a built-in CD-RW or DVD writer for £199 or £269, respectively.

A relatively short battery life could prove to be one issue for OQO users. Our review unit lasted for two hours and 22 minutes in tests using the BatteryMark 4.01 benchmark. These were carried out with power management disabled, meaning that the quoted life of three hours for the standard battery pack is a realistically achievable figure, depending on Wi-Fi use. An optional £139 double-capacity pack should extend the OQO battery life to about six hours.