Yea, this whole "XP only" thing is junk. Ok, I can see it as a promotion to get people to upgrade from Win2K or the millions of people still on Win98, but I mean really - who else are the competing against? Can't they leave Mac users alone?
At any rate, here's another link for getting those two maps if not XP. (They're worth it BTW, or at least Ascendency is)