We have detected that your video card is not supported by Diablo III.
Operating System: Windows 7 Service Pack 1
Video Card: NVIDIA GeForce GTX 580
You have to be kidding me right?
First of all, it's in the supported cards list: http://us.battle.net/support/en/article/D3supportedvideo
Second, I have the latest driver installed (296.10 and even tried beta 301.24) as well as the latest Direct X 11