Will i see an improvement in gaming performance if i upgrade, currently running :
350 watt power supply
6420 core 2 duo @ 3.2 Ghz , fsb 1600
2x 512 modules + 2x 1Gb modules = 3gb ram
8800gt 512 (not overclocked)
2x 80gb HDD in raid
1x 250gb HDD
2x 80mm fans
so far i run most games such as splinter cell conciction, assasins 2, max settings without any crashes. Machine is 3 years old,only recently has the FSB,CPU been overclocked.
You are maxing out your PSU but like Computerrock1 said as long as you are not getting random shut downs I wouldn't worry about it. A larger PSU will add no performance gains. You will only need a bigger PSU if you go with a more powerful GPU otherwise you are good even with your overclock.