The Mac commercials are terribly one sided with only half the story.
I'm not too interested in DX 10 either.. need Vista to get it.. and I have no intention of goin to Vista until Microcrap pulls thier heads outta their butts and gets goin on fixing thei broken junk. I've heard nothin but complaints about it as far as gaming goes.. average Joe user seems to be happy though. "It's not what Vista can do for you, but what you can buy for Vista"- Mac commercial (love that line)
I'm running Vista, and wouldn't go back to XP, the only reason why people complain is because they don't like change.
Though, in your case there is no benefit of upgrading.