Doesn't matter - if it's an oem copy, MS, will be unwilling to activate it. Having said that, if you're determined, xp is very easy to crack, not that one would advocate such a course of action you understand...
My copy of XP Pro is an OEM copy.
It's been through several equipment upgrades and format and reloads.
I guess I've had to activate it 10 or 11 times. Once had to do it by phone with a person, but never a problem.