Vista claims to be a significant update for gamers, but we're staying skeptical until its final release. Microsoft wouldn't hype DirectX 10 and other game technologies just to sell copies, would it? No, rhetorical us, that's cynical.
Use a product key from the RC1 installation, or get a new one from that site if you're new to the Vista expedition. Vista hasn't destroyed any of our computers, but be sure to back up important data or run Vista on a non-critical PC.
See Also: Download Vista RC1 for free, stress your PC and wallet