There are two completely different types of OEM licence. One is not tied to any specific piece of hardware, and may be legally purchased and used as long as it's purchased with a hardware item (this can even include a power cord). The other type is specifically tied to the computer (e.g Dell, HP, Fujitsu, whatever). The first type is much more common (at least in the UK) and is as supplied by all the small "build to order" type dealers. If you have the first type, you don't have a problem. If you have the second, you will know, as it will almost ceratainly refuse to install once it recognises that you have the wrong type of hardware.