Microsoft has changed its licensing conditions for Vista OS, saying it will allow users to run Vista Home Basic and Vista Home Premium as guest operating systems on a virtual machine.

The news means Mac users will be able to install the cheaper consumer-level Vista operating systems using Apple's (now 64-bit) Boot Camp, or virtualisation solutions from SWSoft or VMware.

Mac users seeking virtual Windows have had to buy the most expensive Vista releases, the Business and Ultimate versions.

Microsoft group product manager Patrick O'Rourke told "Now is the right time, we believe, to make it easier for technical experience and see if virtualisation is right for them."

Parallels publisher SWSoft's Ben Rudolph (director of corporate communications) welcomed the move, saying: "We’re glad to see that Microsoft is taking steps to increase the pace of adoption of virtualisation. This shows that Microsoft is committed to the virtualisation market, and we think that this opens new opportunities for us to partner."

Rudolph described Microsoft's move as good for consumers and good for computer users who aren't on Windows as their core OS because it makes virtualisation cost-effective. And, he said, it "makes it even easier for these traditionally non-Windows users to keep their OS of choice, but still integrate with a Windows-centric office".

He added: "Non-Windows users picking up Vista to run in a VM is a good thing for Microsoft, since it puts Windows into the 6 per cent of the market that would normally never be a Windows customer. This is a great way for Microsoft to effectively reach 100 per cent of the desktop market."

Microsoft is also cutting the price of a new product for large businesses that want to run Vista on a server and use either a PC or thin client to act as a terminal to display the information. The new fee is $23 per machine per year.