This may be stupid but I have a genuine copy of windows vista ultimate. I have never activated a copy before and I'm wondering if I activate windows and decide to reformat the computer (which I do at least once a year to keep it running smoothly), does that mean I can no longer use the same copy of windows vista? How does windows recognize that the user is reinstalling windows back onto the machine it has been on? Thanks!
The activation uses hardware serial numbers to make a specific ID number. This in combination with your serial number will be used for activation so if you don't make any significant changes to your hardware there is no problem with reinstalling.