Parallels has added Vista and Leopard support to its Parallels Desktop virtualisation product, which supports multiple operating systems on the Mac - although existing UK users may have to wait, because the downloadable version won't work with the version they have bought.

The update adds Mac OS X 10.5 Leopard and Vista support, and the ability to import operating system images from VMware and Microsoft's Virtual PC, along with a range of improvements previously available only in the beta version of the software.

Parallels Transporter which helps users of PC-based virtualisation products migrate existing settings - including applications, files and profiles - to virtual machines. It also supports USB 2.0 devices (rather than just v1.1) and multiple Boot Camp partitions.

Transporter instantly converts VMware Workstation and Microsoft Virtual PC images to Parallels-ready images. Users can also run their entire Boot Camp installation, directly in a Parallels virtual machine.

This version also features Coherence, which runs Windows applications on the Mac as if they are native applications.

In Coherence mode, the Windows desktop disappears, leaving Windows applications, such as Outlook and Internet Explorer, running directly on the Mac desktop and from the Mac application dock.

“When we introduced Parallels Desktop in April, we blurred the lines between the Mac and Windows worlds. With the introduction of Coherence, we completely blow that line away,” said Benjamin Rudolph, director of communications, Parallels. “We intend to expand the function to help computer users move to a truly operating-system-agnostic desktop.”

In the UK, users who bought a boxed version of software have had trouble downloading the update, but Parallels says they should wait till the new version is pushed to them automatically.

The build versions of the software currently being made available on the Parallels website are "not compatible with UK retail builds (well, the activation keys are not) and should not be used," said a representative. "UK users who have purchased a retail boxed version of Parallels (from Amazon or the Apple store) do not have to download the update from the Parallels website. They should set Parallels to automatically check for updates (or go to Help>Check for Updates) and the update will be pushed down that way, free of charge,"

The representative urged patience among users, as the situation will be resolved in the next few days. "Today and over the weekend, all builds, U.K., U.S., beta, and so on, should all be pushed up to build 3186. This may take time as Parallels only have the one server to get this out."