This varies from title to title, actually. Some applications run faster than Windows runs them. Not games, mind, but others would be a differing story. If you're talking a DirectX8/9 title, it's going to be about half or a third the speed of Vista on a bad day (all of them??). If you're talking an OpenGL title, it's closer to only about 1/3-1/4 as slow at worst.
Heh... I think the implication was that it was as slow as a TNT renders the games it CAN display for when compared to the card he's got.
