This page explains how a proprietary driver for an Nvidia graphics card is installed and configured on (Slackware 13.1) Linux.

1. lspci -v | grep -A6 VGA shows your card type. If 'Nvidia' doesn't appear, you can stop reading now
2. Go to Nvidia driver download page, select your card type and download the driver.
3. Make the installer runnable and run it.
4. If you didn't install the kerel source download it now, it's located in the k series of slackware, for Slack 13.1 it is here
5. Create and config an xorg.conf file. See x-server_configuration_old_way
6. Further edit xorg.conf according to Additional information → README on the Nvidia driver download page:

find the relevant Device section and replace the line:

        Driver "nv"
    (or Driver "vesa")

with 

        Driver "nvidia"  

In the Module section, make sure you have:

        Load   "glx"

You should also remove the following lines:
      
        Load  "dri"
        Load  "GLcore"

if they exist. 

See also http://www.nvidia.com/object/unix.html