Details of Windows Vista's UK price have leaked out online.

Retailers have started accepting pre-orders for Microsoft's new operating system, and early indications are that it's worth shopping.

Amazon's UK site lists Vista Home Premium - the version most consumers will plump for - as £219.99 including VAT for the full boxed product. At Chillblast.com on the other hand, you'll pay £182.11 for the same product. If you want the Ultimate version of Vista, Chillblast will set you back £323.11 with VAT while Amazon is asking £369.99.

Microsoft always said PC manufacturers and retailers will dictate the final pricing, but such large variations are unusual. The software giant has also said it wouldn't announce prices until the end of January, so online retailers appear to have let the cat out of the bag again.

Amazon's US site revealed American pricing for Vista when it posted pre-order details on its site in late August. The prices - ranging from $99 for an upgrade to Home Basic ($199 for the full version) up to $399 for Vista Ultimate - were subsequently confirmed by Microsoft.

As ever, UK prices are significantly higher than those in the US - something this is particularly noticeable this year with the weak dollar. In the US, you can buy Vista Home Basic for $199 - roughly £102 - a full £50 less than the cheapest UK price and a markup approaching 50 percent.

Vista Home Premium is an extraordinary 80 percent more in the UK than in the US.