A system builder (like BottomupWebs) can install a cheaper OEM version of Windows7 on your hard drive. The OEM version can be up to half the price of the retail versions - saving you $$$. It contains the same features as the Retail version - the difference being in the licience.

The OEM licence is only valid for the life of a PC. You cannot move the OEM licience to another PC. You are able to fix the PC without buying a new copy Win7 - however there are several hurdles to jump.

The grey area is when your OEM licienced PC dies and you require a new motherboard. Replacing disk drives and other components shouldn't cause too much of a problem - but the licience does look for the original motherboard. When replacing the motherboard, the computer will need to be taken back to the system builder, and they will need to reactivate the OEM Win7 licience by phone with Microsoft. Unless the motherboard is eaxctly the same, internet activation will not work.