The terms AGP memory and nonlocal display memory are synonymous from the perspective of Direct Draw and Direct Draw drivers.
AGP memory is considered a pure subclass of display memory.
An AGP-compatible driver must check incoming surfaces to see if they are in nonlocal or local display memory, and take the appropriate action.
Although it is out of the Scope of Technical Support for Blizzard to assist, you can search on your own for a program that will tell you what type of motherboard you have, then visit the manufacturer’s website for the update.
Note: The newest service packs may not automatically install when you run Windows Update.
Most video card and system manufacturers provide their drivers as an executable package, which means that the file can simply be double-clicked to run.
If the file that you downloaded is an executable (with the extension on the file name), simply double-click on the file to run the installer for your video card driver and follow through the installation wizard.