Home Built Gaming Rig Needs Some Fine Tuning

My son and I built this system over the summer, but it keeps crashing when I use it to play EQ or WoW or Oblivion.

I have the following components:

DFI LP SLI-D 939 Nvidia AMD Mobo
AMD Athlon 64X2 4800 939 Dual Core Proc
2 GB Corsair RAM
West Digital Caviar 3GB HD
Evga 512 7900GTX 512 Vid Card
Neo 550 Power Supply
4 Fans
Win XP Op Sys

I get a critical error on WoW ...Error 132

Event Viewer in Admin Tools gives me a 1800 Error.
Microsoft tells me I have driver issue...

I am ready to sell the parts on EBAY and go buy something that works. :roll:

Thanks for any advice