PC problems, posssibly mobo or psu. Please help me.

For the past four days may computer has been crashing and rebooting itself when I play games. Here is my specs AMD Athlon 64 4000+, ASUS A8N-E mobo, 2GB Buffalo ram 2.5 CAS, EVGA Geforce 7800GT CO graphics card, Antec True Power 550W PSU. I used to have a case fan but got rid of it because of the noise now I have a case with tons of wholes for heat to escape. I also bought a new fan to blow on my graphics card.

There are two things you should know: 1. my PSU is the oldest thing in my computer at about two years 2. when disconecting my old case fan I may have had my PC plugged in and I tried to discharge myself on my lamenated wooden floor (stupid me). Today I took my PC to my builder and at first it refused to switch on. We tested another PSU and it worked right away. After putting an adaptor on one of cables in my PSU to get a fix it's loose fit it worked just as well. I killed my previous mobo when I put an extra gig of ram in to I probably shocked it.

Two times after my computer rebooted got an error report saying my system recovered from a serious error. Maybe my PC is overheating since I have been getting warning about my CPU fan failing or not working fast enough. Do I need a new HSF for my CPU or do I need a case fan to? I bet I also touched the HSF or ram when I unplugged that god damn case fan.

So what do you folks think have I killed my brand new mobo or do I have a failing PSU. Also note I came in contact with the PSU when I was disconnecting my case fan could I have fried it instead? Today I was playing Half-Life 2 Deathmatch and about 45 minutes into the game my computer rebooted itself. I fear the worst bah maybe I should buy a console and say to hell with computers I feel cursed. :(