You might want to do a forum search on the terms "activation" and "registration" or "activate" and "register". I'm new here, but I'd bet that have been a lot of threads about this on this board. It has been a hot topic of conversation on the Web, and elsewhere, for well over a year, ever since MS started having Office users activate their products.
BTW, the popup that is telling you about having some specific number of uses left is talking about "activation", not "registration". Microsoft requires you to activate but not to register. Big difference. Activation sends no information about you to Microsoft. The OS or the Office app(s) are designed to produce a unique hash based upon the hardware configuration of your system and the license for that particular software product. That hash is transmitted (or phoned) to a Microsoft database which looks for the unique hash in its database. If the hash isn't already there (meaning that that it hasn't already been activated on another machine) the MS database transmits a key which activates the product on your system. Quick, painless, and not an invasion of privacy.
It is true that it might be possible for such a system to be abused -- from the standpoint that a company which makes use of this system might decide that it's time for everybody to upgrade and stop sending out activations for a product. Then, any time you needed to reinstall that product you'd be faced with the fact that you wouldn't be able to activate it. After the allowed number of uses the product would become useless, until it was installed on a fresh OS install on the same or on another computer. I suspect that MS wouldn't do this because of the probability of a huge consumer angst backlash, and the possibility of big time class action lawsuits. But, if someone wants to be paranoid about activation, this would probably be the issue to be paranoid about, not any concerns about it allowing Microsoft to gather information about the end user.
- prosaic