I had a W7 system I activated with no hardware changes whatsoever. The only exception was I unlocked my X3 AMD to an X4 with no issues. Realised the only problem the 4th CPU had was terrible physics in Borderlands 2...limbs would randomly twitch. I turned the lock back on and that single change in my CPU required reactivation. Annoying, but I didn't have to call in.

Kim Jong-il can ride his bike with no handlebars.