Yes, I had to re-install Vista on a laptop due to it being messed up (by the OEM; tons of unstable pre-installed *** that doesn't uninstall). Went to activate, it didn't want to. I called Microsoft, went through the automated system, which took a long time, it couldn't activate either. Was transfered to a human who could barely speak English, had to repeat everything to them, that crazy super long string of numbers, then they told me this key was already installed on another PC. I said no. He insisted, then I got angry and told him I was looking at the genuine sticker on the laptop with that key and it had security features like a weaved metalic strip. I asked: do I have to send you a photo? Do I need to involve the police? Do I need to go to court to activate my copy of Vista?! So he read me the long sequence, in broken English, no less, to activate it. Basically an hour of my time wasted, not to mention a lot of frustration.
This entire Vista experience has left a very bad taste, between Microsoft and the OEM I feel I have lost total control over my PC experience. I am fed up and so ready to jump ship now.