AMD have a more sophisticated tech in their hardware. The problem is that it really hinges on their shader compiler speed. Technically they should blow Nvidia out of the water but there is something clogging the sink. Nvidia usually has a wide open valve, even if sometimes they let IQ falter in the process. ATI drivers usually act like an injection of Drano. I don't upgrade my 7800GT drivers all that often, because there is never a real improvement in speed so I gave up. Also, there are a lot less bug fixes in games because a lot of games are made on Nvidia tech. ATI on the otherhand, I upgrade every patch because even if they don't have major fixes for hardware in that particular version it usually has a slew of game fixes.