Was it a copy of Windows XP from a major vendor like Dell, HP, etc? Not all OEM copies are like this, only the ones from the companies that move a major percentage of computers. Generally the ones like this will say Dell or something directly on the disc, but not always.

And Mark, it was explained to us as a method to also stop piracy when we got trained on it. This was back when Gateway started doing it around the time Windows 2000 and ME were shipping. We had the "proper" things to say to a customer if they were getting certain errors that indicated it was loaded on a non Gateway box. Back then the thought process for the piracy part was to prevent Joe from buying a new computer, and sharing the new OS it was likely to have with his neighbor Bob.

Thank <diety> I'm not in consumer tech support these days.