Dedoimedo posted a tutorial explaining how to install the Nvidia drivers in Ubuntu 13.04 family

This is a very important tutorial. The last several releases of Ubuntu are less than stellar when it comes to installing Nvidia drivers on your machines. You are likely to end up with an unbootable system, just by using the same methods that used to work flawlessly in the past. To wit, this very detailed guide, which should save you a lot of trouble.

I will present you with no less than four methods, starting with the easiest and slowly escalating toward the more difficult and less obvious ones. We will also examine a few other techniques, tips and tricks, learn about recovery, backup, and more. This article should be your one stop shop for all current and future Nvidia drivers installations.

  How to install Nvidia drivers in Ubuntu 13.04