The rumours about that have been going around for quite some time. A friend of mine that works as a college administrator downloaded the last available Vista beta, and I already talked him into running some tests with me. Guess it's confirmed now, so I don't have to run those. Probably still gonna do it
One thing we should note, however, about Vista and old games(younger than DX9c): they'll be running in some kind of simulated support mode. Apparently, DX10 was built from ground up(I know, sounds incredible for Micro$oft to do that, but they did), and has little support for anything previous. So basically, newer games will run better than the older games.