Stuttering!

[Poisnchild]

Hi everyone. I'm getting some very annoying stuttering in-game. I thought it was lag at first, since I was connecting through my wifi card. Well, now I'm connecting through my ethernet port and the same problem exists. I have tried low and high settings to no avail. When detecting optimal graphics, it sets the game on very high. I've read through some previous posts and disabled my ATI HD audio device, but still having this problem.

Basically, when running around, the game plays smooth for a couple of seconds, then slows/stutters for .5-1 second. It makes the game almost unplayable. At times I've had it freeze as well. I'm not sure if this is from having a cheap gfx card, lag, crappy ati drivers or what, but I'd love having it play smooth. Has anyone figured out a fix for this issue? Maybe someone with similar or same hardware? Crossing my fingers! Thanks for your time

Specs:
Athlon 64 X2
Sapphire HD 3650
4GB DDR 800
Vista Ultimate 32bit