Hi Master-of-Doom...
you won't need to rebuy XP but you will need to call them to explain the hardware change and answer a few questions then they'll issue you with a new key which you can reactivate your copy of XP with.
you won't need to rebuy XP but you will need to call them to explain the hardware change and answer a few questions then they'll issue you with a new key which you can reactivate your copy of XP with.