I have heard some rumors that the developers of WINE (windows emulator for other OSs, and don't gimme that Wine Is Not an Emulator guff
) might create a compatability layer that would allow DirectX 10 games to work on Windows XP. I don't know how that would be done, or if it would be done, but it is a possibility. DirectX 10 is cool and all, but I don't see any immediate need to upgrade to Vista. In fact I would be willing to bet that by the time games begin to require
directx 10 that a solution will be available for xp.
BTW, if WINE does come to the rescue I'll be really happy, I won't need to reboot into Windows to run may games anymore