IMO I think you would be better off get the drivers from ATI and use them. I have had better results with getting the propriatery drivers for those cards. Nvidia drivers come with a graphical X configuration utility after you build the kernel module driver. Optionaly you can run "system-config-display" with the deafault configured X config and select the ati card. Also if this is a duel monitor output card, that could be where your ((NO Screens Are Found)) Error. Post your Xorg.config file.