My understanding is that the history is flushed 6 months after any change, and it takes (IIRC) four nontrivial changed components to trigger The Call. So, if you change your network card and hard drive, then six months later, it'll consider itself a virgin installation.
I think a lot of the people screeching the loudest (which I do not consider you to be doing) are "casual pirates" who won't be able to do multiple installs off one key. The amount of piracy is staggering, and as with all forms of theft, it's the rest of us that pay for it. If someone has a better idea of how to deal with it, I'd think MS would be all ears.
I'll bump that. Think how much cheaper Windows and Office would be if all of Asia wasn't using the same disks.