I had the same sort of troubles trying to install Nvidia drivers for my 6600 card. I wanted to get twinview happening - thats a different story, though and would require a bottle of Jameson whiskey for that one to go down!
Anyhoo, I traversed (read: trawled) through countless articles and whitepapers telling me to do this that and the other thing, but nothing seemed to work.
Then, I found that the second post in the Ubuntu forums points to this site: http://easylinux.info/wiki/Ubuntu:Edgy
This showed just about everything - INCLUDING how to install the drivers.
My bet would be to try there, and see how that goes for you. It worked for me, and now I am able to spend countless hours playing lovely crack-attack and foobillard!