UK prices for Windows Vista are double the prices of the US.

Vista Home Basic upgrade: US $99 = UK £100 ($195)

Vista Home Basic full: US $199 = UK £180 ($352)

Vista Ultimate full: US $399 = UK £370 ($722)

If you're happy to be ripped off then you might want to check out this guide: Which Vista Edition is Right for You?

You can get far cheaper OEM versions from Novatech.

M$ have acknowleged that the whole OEM scenario is open to abuse as many peeps are now classing themselves as "system builders" to enter the loophole.

M$ have therefore stated that by the Autumn (Fall to them) they will have closed that one off. So in the meantime OEM away.