That is an old board and an old socket that doesn't support an new CPU's. You could pickup a Core 2 Quad Q 6000 series for about $50 on Ebay, but depends on what you already have in there for a CPU if it's worth it or not. Are you using DDR2 or DDR3 ram with the board? Graphics card, you can't go too high or it will bottleneck the CPU.
Honestly, I would build a new PC. That board doesn't have a lot of room to go anywhere fast enough for todays games.