Annoying Glitches in Quake III with VooDoo 3500 AGP

Hi, I have a Voodoo 3500 AGP, and when I play Quake 3 i get annoying serrations on brushes and weird glitches- heres a screenshot
you will notice the serrations on the sides of the gate there. I tried turning GL extentions off to see if thats the problem and it didnt seem to make a difference
Im using the latest drivers etc and my system is working perfectly.
IF you have any idea how to solve this please mail me