I really wouldn't worry. There is a chance you'll have to run the activation wizard, but in the countless times I've made changes the activation is done in under 30 seconds. The OP's experience is very very rare.

In the even you've already activated the same key more than 5 times you'll have to call in, and 5 minutes later you'll be done with it. I have a test key here I use on machines which has been activated over 40 times, and they haven't turned me down once.

Of course the activation system is a PITA, but like one of the previous posters said, theft of Microsoft products is a major problem and one can't blame them for protecting their assets.