OK so I just got Ubuntu the other month or so. I'm running the 11.04 version currently and trying to install drivers for a Nvidia graphics card (it's my brother's computer and he currently cannot find the number of the card right now). I read that, to install the proper drivers for gaming, I would need to go into "Additional Drivers" and choose them myself. I clicked to go into "Additional Drivers" and it searched "for available drivers", then opened the additional drivers list. Lo and Behold, there was nothing, simply the message "No proprietary drivers are in use on this system" and the Help and Close buttons. Sorry if there's some silly simple answer to all of this, I'm new to this sort of thing (used to Windows simplicity, lol) and I really don't know what to do. Help would be much appreciated.

Also, I should mention that the graphics card was installed and ran fine before switching from Windows XP to Ubuntu.