Microsoft's web site for UK customers looking to pre-order Windows 7 at a discount goes live Wednesday, but the firm is warning buyers that stocks are limited and will be allocated on a first come, first served basis.

As reported on V3.co.uk previously, Microsoft is making Windows 7 Home Premium and Windows 7 Professional available at substantial discounts for UK buyers prepared to pre-order.

Under this offer, the two editions will be available at £49.99 and £99.99 respectively, compared with the full prices of £149.99 and £219.99.

The web site will be taking orders from just after midnight on 15 July, but customers will not receive the software before the launch on 22 October.

Buyers can also pre-order from partners including Amazon.co.uk, Argos, Comet, Currys, Dixons, Ebuyer.com, John Lewis Partnership, Littlewoods, Micro Anvika, PC World, Play.com, Staples and Tesco.

Meanwhile, Microsoft has confirmed that volume customers will only have access to Windows 7 from early September, despite the fact that the operating system is expected to be released to manufacturing (RTM) at the end of July.

"At RTM our partners begin their final preparations for Windows 7, including testing and building images for new PCs," said Windows communications manager Brandon LeBlanc in a blog post.

"RTM is essentially the final 'stage' of engineering for Windows 7 before it hits the market at General Availability. Engineering continues on Windows 7 from RTM until General Availability on 22 October."