Windows Product Activation (WPA):
http://aumha.org/win5/a/wpa.php
Quote:
The hardware is checked each time Windows boots, to ensure that it is still on the same machine. (...) WPA asks for ‘votes’ from each of these ten categories: ‘Is the same device still around, or has there never been one?’ (...) If you change the device in any category, you have lost that Yes vote — but will not lose it any more thereafter if you make changes in that category again. So, for example, you can install a new video display card every month for as long as you like.
Interspersing your changes with restarts won't allow you to 'creep up' on WPA... but it sounds like you've already gone through a couple of video cards, so swapping in your 6600GT now isn't going to 'count' against it.
Quote:
If, on Windows startup, there are not the required seven Yes votes... The system will continue to boot normally for three days, during which time you will be able to contact the activation center via the net. If the extra changes have been removed, or if 120 days have passed since the original activation, you will be able to use the automatic process
I had to reactivate after getting a new mobo. Involved all of, connect to the internet and click. That was it.
Can't help with your registry/window problem, sorry.
