[Gordon]

In the case with Vista, you can phone in and have your abuse level reset so you can install again. It's three major hardware changes that confuse the system, generally involving the motherboard, processor, and HD, but can also be set off by an upgrade of the video card.

Anyways, if that were the case I assume there would be a similar system for resetting the installs during the activation period like there is with lets say... Antiviruses and what not.