tinivole has put together all the instructions to solve problems when using NViDIA video cards of the 8400 series and up. He is actively supporting his tutorial and many people have given input. Debugging steps are suggested if all does not go as per the book, as well as reverting the changes and going back to the ubuntu supported drivers.
The tutorial is located here: HowTo: NViDIA 185.18 Drivers in Ubuntu
Enjoy and see you soon :)