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#51
I don't (and can't) know. However they send some sort of fingerprint based on hardware/software which (presumably) matches what is on their servers.
I mentioned genuineticket.xml before as that is the info they want when you upgrade. I guess they store this and I'd be surprised if your HWID on their server didn't link to details of original system and license.
I'm just speculating of course. Perhaps they don't store it and just throw it away or perhaps genuineticket.xml contains nothing of interest apart from a "this Windows 7 Professional install is valid" y/n flag.
As to the question, ianal but if MS allow it using their documented methods (with no tricks or fiddling) then I guess it must be OK. If they don't know that is their problem and if they do know (which I think is more likely) but don't enforce it that also is their decision.
Business/Academic users have volume agreements and most home users use the version that came pre-installed so the number involved in transferring licenses like this is, I suppose, relatively tiny anyway.