If you're itching to get your hands on Windows Vista, and can't wait until the 30 January, then one online retailer has the solution: OEM versions for sale already.

Overclockers is selling OEM, or Original Equipment Manufacture, copies of Vista, which are designed to be installed by computer retailers and not sold as standalone software.

However, buy an OEM version could save you money. Overclockers is selling the Home Premium edition for around £78, while the Ultimate Edition is on sale for £135. That's a lot cheaper than the retail version that cost £220 and £350, respectively.

The company also offers Office software and Microsoft XP and Media Centre as OEM versions.

The legality of selling OEM copies is a bit hazy, but keep in mind that if you buy one, you won't be able to receive any help or support from Microsoft.