I am ready to buy a new graphic card but I am confused between GTX 580, AMD 6970 or GTX 570. Last year I made a new Desktop which is listed below what you all think would be the best Graphic Card with the system below. I do plan to keep the GTX 280 to place it as a Dedicated Physx Card. I know that there is a way to use Nvidia and AMD cards together as one a Physx card. Any help, suggestion, comment would be greatly appreciated.