Microsoft takes several years to produce each new version of Windows, but Apple likes to upgrade its Mac OS X software on an almost yearly basis.

Version 10.4, also known as 'Tiger', is one of the biggest updates so far, with around 200 new features. A lot of these are rather obscure technical changes, though, so Apple is putting most of its focus on a handful of really eye-catching new characteristics.

The feature that Apple seems to be most pleased with is Spotlight. This is a powerful new hard disk search tool that can not only locate files with a particular name, but can search the actual content of the files.

Digital photos, for instance, can contain 'keywords' such as the date or location where the photo was taken. Spotlight can search for these keywords, allowing you to locate all the pictures taken in 'Barcelona', for example, or all those taken in May 2005. It can also delve into spreadsheets or even PDF files to see if they contain the information you're looking for.

However, our personal favourite is The Automator, a kind of very basic programming tool. It provides you with a list of predefined 'actions' that can be used to control programs such as iTunes or the Mac's iMovie video editor.

You can use these actions to automatically perform tasks such as grabbing some songs from an audio CD, converting them into MP3 format and then adding them to a playlist.

It's a great timesaver for routine, repetitive tasks, and you don't have to be skilled to use it. You can also download new 'actions' from the internet to control other programs such as Microsoft Word or Adobe Photoshop.

Another handy timesaver is new the RSS option within the Safari web browser. Also known as 'really simple syndication', RSS is a system that allows websites to provide you with a 'news feed' of regularly updated stories.

The RSS feature in Safari can now automatically detect the news feed on any website and turn it into a web page that contains convenient summaries of all the latest news stories. It can even combine RSS feeds from multiple websites, allowing you to create your own personalised news digest.

You can customise a Mac even further using the new 'Widgets' feature. Widgets are small programs that perform specific tasks, such as checking the weather forecast or (our favourite) providing a list of all the local wireless hotspots.

These Widgets are hidden most of the time but can be instantly activated simply by pressing the F12 button on the keyboard. Apple includes about a dozen Widgets with Tiger, and there are dozens of others that have been written by Mac users, which you can download from the internet free of charge.

Tiger also includes updated versions of programs such as iChat, the instant messaging program that can now conduct four-way video-conferencing sessions (although you'll need a fast Mac and a fast internet connection to pull that one off).

We've had our doubts about some of the previous upgrades to OS X, but Tiger suggests that Apple is really hitting its stride right now, and we can definitely recommend it as a 'must have' upgrade for anyone that owns a Mac.