erm.. I'm sure this is just a ploy to deter people from pirating.. as Keygen for win xp came out about 2 years ago, it generates new keys that has never been used before.. so how would MS know which is which?! they just makes it a bit harder, that's all..
They only block those keys that are established to be piraters, which is a very very small percentage.. i stlil don't see a future in MS's anti-piracy technology..