As the operating system appears to be getting more and more unstable, I think it's time we got rid of some updates and replace the system files. This will leave your data intact and will use the drivers currently installed for your hardware. If this is a hardware issue, it's deeper than the video card.
Boot to your Dell XP installation cd. At the Welcome to Setup Screen, press Enter.
Press F8 to accept the License Agreement.
Press R to repair the currently installed operating system.
If you are asked for your product key during this procedure, you should find it on a sticker on the left side panel (desktop) or bottom (laptop) of your machine.