Thanks everyone for taking the time to help out. I spent about an hour on the phone with a level II tech rep with Nvidia. Ray was extremely knowledgeable and we tried several different clean and manual installs, still no joy. I have not lost faith in Nvidia because it sounds like it could of been a very rare instance of video card damaged by driver, and they may work out a deal to help me replace it.
In the event they don't, I am open to any other ideas, even though the tech reps seem to agree that my 9800GX2 is fried.