If you are looking for the driver for your graphics card, you can get the driver and installation instructions from
this page. Based on what you said your graphics card was you should choose GeForce and GeForce 8 Series. It is almost certain that unless you know otherwise (check the name of the file you downloaded that contained Mandriva 08) you should choose Linux 32-bit. If you scroll down far enough there are instructions.
It might be better, though, to download Ubuntu Linux which includes a "restricted driver manager" which will automatically download and setup the driver for you. You can get Ubuntu from ubuntu.com and once you have it installed just click on the "System" menu at the top and go to "Administration" and choose "Restricted Drivers Manager."
Hope that helps!