The already-excellent Mac virtualisation software Parallels received a major update today. The new version adds support for 64-bit addressing, multiple CPUs or cores, 3D support, and has a spruced up UI. The company reckons the multicore support and other optimisations offer performance improvements of 25 per cent over earlier versions.

The growing popularity of Mac hardware, allied to the pains of running Vista, means a larger potential market for software that permit users to run Windows applications seamlessly on Mac OS X. It's also led to ferocious competition - with low prices and regular improvements to the leading competitors.

VMWare offers its Fusion Mac product for £49.95, the same as Parallels. Parallels is offering a special offer upgrade for existing users of £24.99 until the end of the month, after which it goes up to £31.99. A new 5-seat option is introduced at £199.

So what's in v4? One of the banes of users who use a virtual disk partition for their VM is that the Leopard backup program copies the entire file (usually gigabytes in size) every time. This can be turned off, and a bundled Windows backup program used instead.

Other new features include booting from a server image (via the network adapter), security zones, automated snapshots and a bundled anti-virus program from Kaspersky. One slightly irksome new feature is the incorporation of Windows system tray applets into the Mac menu bar. You can turn this off, though.

You'll still need to bring your own copy of Windows.

Parallels' parent company, originally called SWSoft, is also known for its Plesk website administration program. ®