I tried Vista, it's cool. Even with 512mb of RAM, it runs well. This thing about DRM and stuff is not a nightmare. I guess you can turn off that shit by tweaking some services. Vista is, definately, a good choice.
But...
As the doc says, vista has decreased playback quality. But i guess it's not to be worried about. Our currently hardware won't even handle vista at it's max. So, for me, that's not a prob.
And the other thing that scares me is Vista performance with games. I didn't try games on it, but I heard they'll slow down, comparing to XP. Since my PC is for gaming too, I feel afraid of updating to the new OS and getting fucked to play games.
So, right now, I'd/I'll stick up with windows XP. It's satisfying my needs, both in performance and gaming. I might install Vista in some small partition (if you can say that 15GB is "small" for an only 40GB HDD) to try out the new DWM and Aero.