|Told you that downgrading to 32-bit wouldn't help. |
However, you first mentioned GTA SA. If you're playing GTA 4, your processor is slowing you down. GTA4 is a game that likes quad-core CPUs, or dual-core processors with hyper-threading.
Which anti-virus software are you using?
Super PIII | Unlocked ES Tualatin @ 1.8GHz (150x12, 1.65v, 512K L2)
2GB PC2700 | 500GB | Radeon x1950Pro | Apollo Pro 266T | Win 7 Pro