First fill out your system spes in you user CP top of page. We need to know all your hardware. Second you have an Nvidia 6600gt and you mention removing all the ATI drivers What??? Which drivers did you install and I assume you did this before you restarted. First try and startup in safe mode. Then uninstall the display driver, Restart and let windows install the driver. You might be having resolution problems because you don't have your monitor driver installed , it would be listed under display in device mngr as PnP if this is correct. If so find and install the display driver if their is one. Can't help you with this, without knowing all your system specs.
Also the build # and 32 bit or 64 bit 7 version. Just need more information.