For my ATI card, the drivers add in tabs to the video card properties where the AGP bus multiplier can be manipulated. Go to your display drivers, then chose the "settings" tab and select "Advanced". If you can't find it anywhere in there, then I'm at a loss for further advice... beyond getting a new MB & VC, but if you're gonna do that, you might as well get a new CPU & RAM (DDR if you're not using it already) at the same time. I know a 2 GHz CPU isn't exactly nothing to sneeze at, but we're talkin' about a Celery here. Trust me, a full fledged P4 or Athlon(64) is the way to go over a Celeron/Duron/Sempron. For the MB, again... match to your desired CPU, RAM, & VC in terms of expansion slots and upgradeability (Serial-ATA is a must, but retain P-ATA for legacy devices).
Well what'd'ya know, I started out trying to diagnose a graphical error and went on to advise someone I've never met to replace the bulk of his computer, just because I hate on-board video & audio with a vengance. I hope I didn't make you feel too inadequate over that. For your sake however, I hope you have sufficient funding to consider my proposal.
Later!
