Windows 7: Re-using XP after upgrade

My step-son has XP running on his PC. When we upgrade to 7 Home Premium will the XP license validate on another PC ?
As it has in effect been un-installed then I can't see why not but I'm baffled enough by Upgrade, Full version, OEM etc.
Any help much appreciated,Nelly.

OEM Versions are only legally licensed for the PC it was delivered with or the PC it was first installed on.

Other versions MAY be able to be reused on a different PC. You will probably have to contact Microsoft to try and get it activated on a different PC.

However, seeing as how XP is basically "dead" (Microsoft has stopped issuing any fixes for it and will stop all support either this year or next) and has some gaping security holes, do you really want to reuse it?

If the PC is one that was purchased with XP on it, then most likely the license is OEM and cannot be used on another machine. Even reusing it on the same machine that has a new motherboard installed is iffy at best (it depends on the mood of the M$ tech you talk to).

If the license was purchased separate from the machine, then it would depend on if it was OEM or Retail. As long as the previous installation is deactivated, then a Restail license can be reused on another machine (I don't recommend doing that unless it's intended to be temporary since XP will reach its end of support 04/14/2014). If OEM, technically, you can't reuse the license on another machine although many have had luck sweet talking M$ into allowing it. Since XP is "dying" soon anyway, I wouldn't bother. If you haven't bought it already, I would suggest getting a retail version of Win 7, even though it costs more, to ensure you will be able to transfer the license in the future, especially if M$ tightens up their restriction on reusing OEMs (something I expect will happen based on the direction M$ has been heading lately).

Thanks for the quick reply both of you and for clearing that up for me.
So from what has been said : I still have a key/CD for an old Dell and the key/CD can only be used to install to the same Dell ?
Looks like I'm going retail Win 7 Home Premium.

On a Dell OS Disc, it is tied to a Dell BIOS and will only install on a Dell motherboard (PC).

Thought so, thanks.