I'm bummed I need Vista or Windows 7 to play. If I'm going to upgrade to Windows 7, I'd like to go to the 64 bit version. But as we know the 64-bit version doesn't work with Aces High.
IIRC, you can load two OS on one PC. I'm not sure how, but the geeks can help you with that.
IMO, you should upgrade, I have Windows 7-32bit and want an upgrade myself, but I have no problems so far, so why fix something that's not broken, right?
Windows XP is getting outdated by the second, and in 2-3 years, Vista and 7 are going to be the norm with Windows 8 at the top. And besides, lots of games uses DX11 to great effect these days, I'd say go for it.