Inbox:It has been a long-time since Apple launched a brand new operating system. It was March 2001 when they switched to Mac OS X and the difference with OS 9 was palpable, writes  Mike Butcher

Just about everything in the Mac world changed that year, and since then, Apple has arguably done more with its operating system than Microsoft did with its "giant leap" to Windows Vista, which was late and has been beset with problems.

So what can we expect from the new Mac OS X?

Delayed by seven months because Apple was weighed down by trying to launch the iPhone on time, Mac OS X 10.5, better known as Leopard, has more than 300 new features, and so far, those Apple users upgrading to it are finding the experience pretty smooth, judging by many blog entries.

While there are many changes, the upgrade is really very close to the existing OS X and nothing like the leap from Windows XP to Vista, which perhaps explains why it has been an easy transition since the launch last week.

The first thing that you notice with Leopard is that, graphically, it has been given an even slicker polish than the previous OS, which was reasonably good looking to begin with.

The Apple dock which keeps all your favourite programs and files is now in 3D. Plus, the Coverflow feature, which we first saw on the iPod has been extended to the entire Mac desktop. This means you can now browse files and applications in a very graphic manner, leafing through them as you would an old album collection.

You can also play a file from within this Coverflow view without even having to launch the full-blown application. That makes working with the new Macs - on which Leopard will comes pre-installed - much faster. A further time-saving feature is that every file has a preview image, so in many cases, you do not need to open it to find out its content.

There are three more main changes with Leopard: Stacks, Time Machine and Spaces.

Stacks is a way of grouping together several programs into categories such as home or work.

Time Machine is a system to automatically back up your files on an external hard drive. There have been third-party applications available to do this for some time, but now Apple is stamping its authority on its own solution. Plus you can literally "go back in time" to find files that you might have since deleted.

Spaces is going to be a godsend to people like me who are terrible at keeping their desktop tidy. It divides your workspace into up to 16 desktop screens, each of which can have different applications running. It sounds confusing, but it means you can set up a screen for "home" or "work", for instance, and keep both separate.

There are so many more features to Leopard that it's hard to go through them all here. But it is clear that the new system packs a lot of punch and will enable you to do many more things with your Mac. For that reason, it's almost certainly worth the €129 upgrade - with one caveat. If you can afford to wait a couple of months, any underlying bugs (though none have proved at all significant so far) will have been be ironed out. It's always the way with any new operating system. Just ask the many Vista users who are busily looking for ways to convert back to Windows XP.