I had trouble with frame rates in flight simulator in 7, so I wanted to change the video driver from the one that MS installed during the installation of 7. The first time I grabbed an nvidia driver and installed it, it went just fine, but frame rates still sucked. Later on, I searched for another version of the nvidia driver and downloaded one. Then, trying to be clever, I uninstalled the current nvidia driver and windows installed the plain vanilla VGA driver. With the VGA driver running, Nvidia setup was unable to detect that I have an nvidia card installed. I quickly deduced that was the problem, and let windows reinstall the WDM driver, so that the Nvidia setup would detect the card. It did.