nVidia is good card company, but replace that 4200 pronto, i'd say get the 6800 if you have the money, but a 5600ultra or even a 5950 ultra (they are cheaper now) would be good. You could also try ATI Radeon 9800 series too...

Proc is OK, I would overclock or replace with a 3.2gigger. The extreme series is a total waste don't buy it unless your wallet is the size of Bill Gates'. I would get a 3.2 gig 800 mhz bus (Northwood? not as familiar with P4's).

Your system would kick bigger/better ass if you replace that video card pronto! The 4200 is dragging you down, and you wouldn't be able to play games like Far Cry, or even Half Life 2 down the road.

Oh yeah try a PC Power and Cooling power supply. I suggest the Silencer 410, it has a 12v connector for the more advanced mobos, really good quality stuff there. About $85.