|With Xp and above there may also be licensing issues involved. Technically all retail copies can be transferred, but it may mean calling Microsoft support to activate over the phone. Activating over the net sometimes refuses to work with a message along the lines of "this copy of windows has been activated too many times".|
Oem copies are more of a grey area, I heard they will normally transfer the license, but supposedly don't have to.
When I transferred my retail copy of XP home even activating over the phone refused to work, I had to choose "if you believe this is an error press x" and talk to an operator.
I always clean format and reinstall if I need to, so I'm unsure if a repair install requires reactivation...
It's a pity, because win98 used to handle having the disk swapped quite well in most cases, I've had an ubuntu install handle it well too. I doubt they couldn't make it work modern windows, it's just a very handy license enforcer.
Batch Variable how to