andokai wrote:

Anyway how about this scenario. I have an OEM copy of XP running on a 32 bit machine and a studnet copy of XP running on a x64 machine. Can I exchange the OEM copy for XP x64 install that on the x64 hardware and then install the student XP on the 32bit machine?

No, the OEM licence is tied to the hardware it was supplied with.

If you're a student studying a computing based subject (which I'd guess you are given that you are here) why not ask if your department is a member of MSDNAA and if not, why not?