danny there three version of windows. the oem that you see that most times must be sold with a computer part. the oem of windows can only be used for one pc and is locked in to the hardware of that pc. the retail version of window lets you reinstall it to another pc if need to. the retial version and im going off from my hip here lets you reinstall it 7 times before you have to contact ms for a new code. the last version of windows is for prebuilt vendors like dell and hp. there sold a large block of windows code and there image does not look for a oem number but a vendor id that flashed into there hardware. if these install programs dont see the right hardware they wont install the os.
as you have a new pc your better off skipping 7...