Games stuttering

[Kalmado]

My desktop is stuttering while attempting to play some games. Specs will be listed below. I don't get any stutter with Dead Space or Half Life 2, but I do on some others. The worst, surprisingly to me, is GTA San Andreas. I get a stutter every 4-5 seconds. Doesn't matter what I'm doing. Right after you start the game and the cursor is hovering over the bike you can watch it stutter constantly at the 4-5 second mark. Any idea what would cause this?

hp pavilion desktop
amd phenom Q4 1.8ghz
4gb ddr2 ram
ATI sapphire 4830 512mb dedicated

[Kalmado]

Uggggh, apparently the stuttering is a known problem with GTA San Andreas. Found some things that seem to improve it. I'll assume my turd of a desktop makes my other games stutter. If anyone has any tips I can do for improvements let me know!