Originally Posted by Melcar
I remember reading something about MS "relaxing" the license on OEM copies. I constantly switch out the mobos on my Win machines and they are all running the original OEM copy I got for them initially (one for each PC of course). Don't know if Vista is any different, but I doubt it is. If upon reactivation it asks you to call, chances are that the costumer service rep. will give you another key (they did for me twice when I upgraded some machines at the office).
It was relaxed for components, but not for the motherboard.
As said above, it can be done, but it is against the TOS that you agree to with you hit F8 when installing Windows, so it is technically pirated software. It is the same for XP and Vista, and has always been that way with any OEM Windows (I know 98, ME and 2000 had OEM and Retail versions, not sure about 95 and earlier).
Just because MS gives you another key does not make it any less pirated. They are trying to keep legit customers happy so they just give the new keys out.