At its recent World Wide Developer Conference ( WWDC ) Apple took the wraps off yet more features in the new version of its Mac OS operating system - known as Leopard or Mac OS X 10.5. But surprisingly for Apple, a lot of Leopard seems terribly familiar. And that's unusual for a company that trades on its reputation for innovation. Like Windows XP, Leopard has a default grassy-green desktop and like Vista it has a transparent menu bar. It's also opted for a Vista-like 3D effect on the Dock (the OS X equivalent of the Start menu and Taskbar).

But beneath the surface it's soon apparent that Leopard has a depth that Vista lacks. For example, there's Time Machine, a great back-up utility that runs silently in the background, continuously copying your data to an external drive. Should you accidentally delete an important file then you can simulate going back in time on your Mac to restore it. Vista's backup features are good, but they've come under fire for not being comprehensive enough.

What does it offer?

Spaces is another improvement over Vista. It enables you to create several virtual desktops, or 'work areas', and switch between them, so you can work on multiple projects at once while keeping them separate. Also new in Leopard are Stacks, these are folders that reside in your Dock and expand to reveal their contents when you click on them.

iTunes 7.2 introduced Cover Flow, enabling you to flick through your album artwork as if you were flicking through a physical CD collection. In Leopard this functionality has been extended into the Finder (OS X's version of Windows Explorer), so that you can flick through thumbnails of your files in exactly the same way. It's clever, neat and quite compelling. Apple has also incorporated a brilliant method of instantly previewing files without opening them, called Quick Look. Using Quick Look you can browse through multi-page PDF files and even play videos, all without opening the file into the relevant application.

Webcams are built into most new Macs and Apple has geared-up Leopard to take advantage of this by adding some fun new features into its instant message client, iChat. You can now insert video effects like an X-Ray, or Glow to your face. And you can even blue-screen your image over a background of your choice, so it can look like you're calling from the Bahamas even if you're in Birmingham.

How innovative is it?

So, while Leopard is undoubtedly eye-catching and beautifully implemented, is it really as innovative as Apple would have us believe? Virtual desktop systems like Spaces have been a feature of just about every Graphical User Interface (GUI) of Linux for years now. And while Time Machine has a gorgeous 3D interface, backup isn't anything new. Similarly, transparent menus and 3D elements are standard fare in today's operating systems.

Is Leopard better than Vista ? Of course it is. It's more secure, has superior features and it's easy on the eye. You don't have to make the difficult decision of which version you should buy either, since it only comes in one flavour (plus a Server edition). And you're not forced to go through the agony of product registration once it's installed.

So, should Microsoft be shaking in its boots? Ultimately, no. The biggest problem Leopard faces is that you still need to own a Mac to install it. If Apple freed up its overly restrictive software licensing terms then Microsoft could have something to worry it. But until that happens Leopard remains purely of interest to Mac owners, who will always be a very vocal, if very well served, minority. Timo Arnal