Overheating? Need input!

I built a new system about 6 months ago, no real issues till now. My friend convinced me to get WoW, and I decided I wanted to refresh my HD with a nice zero out and fresh Win XP Prof 32-bit install. During the install it just randomly shut down. I ran it again, and it happened again. Checked to make sure nothing was loose, resat the heatsink on the CPU and it finished the install. Played WoW for a bit and it just randomly shut down again. Speed fan showed my CPU running a little hot, so I cleaned off the CPU (I work in precision cleaning so I have access to 99.9% Iso/Alcohol), applied new Arctic 5 thermal paste, CPU is pretty steady at 30 C - 40 C depending on what I do. The video card was running very hot however (50 c - 58 c).

Here are my specs:
Thermaltake Armor full ATX with 2 120mm, 2 90mm, 1 250 mm fans
Rosewill RP600V2-S-SL 600W SLI Ready-ATX12V V2.01 Power Supply
2.4ghz Intel Quad core LGA 775
4x 1 gig Gskill DDR2 RAM (granted, only recognizes 3 gig as it is the 32 bit XP)
MSI P6N SLI-FI LGA 775 NVIDIA nForce 650i SLI ATX Intel Motherboard
MSI NX8400GS-TD256E GeForce 8400GS 256MB 64-bit GDDR2 PCI Express x16 Video Card

I also have the BFG NVIDIA GeForce 8500 GT 256MB PCIe video card, which I switched out the MSI VGC for, and I just bought the BFG NVIDIA GeForce 8800 GTS OC 512MB PCIe 2.0 (which I am now returning) and all 3 video cards ran very hot. The 8800 GTS also wound up making my CPU run about 10 C hotter than the other 2. I am at a loss. Speed fan shows the system as fine, only the VC is burning and the only conclusion I can come to is the PSU. Even then it still doesn't make much sense why it runs everything perfectly fine aside from my video cards when attempting to game (mind you, it is WoW, not Crysis. Shouldn't be killing the card). I have a total of 5 fans, 3 od them are large fans, the ase runs very cool and is extremely clean. Thermal paste is fine. Very annoyed.

Thanks in advance for any help and explanation as to what would cause the PSU (if that is the issue) to be this spastic in what it over exerts.

Going by what you have already said, I can only think of two things... one is that you said you was using a 64-bit video card... compatibility issues with the new 32-bit operating system you freshly installed? might run fine without a full load, but add "WoW" and it could get hot! Or even compatibility with the MB?
I know it should not really matter, but sometimes comps can be touchy.

Another potential problem could be fan direction... Are all the fans working together? If one is turned the wrong way it could cause an air flow problem... I'm sure thats not it, but I've seen it before..

"I want to live my life so that my nights are not full of regrets."

Firstly, I'm no expert, I did take Tech classes, but I will give it a shot...

I'm sure you have probably cleaned out any accumilating dust, since dust build up will cause a PC to shutdown automatically to prevent damage to the components.

Is the PSU you have able to handle your "hardware?"

5 fans are ok. 6-7-8 fans is where it gets a little too much. However, the fact that 3 of your fans are large--that could be causing some air flow issues.

Could there be a BIOS-related issue here?

Could it be a virus? Be sure to back up all important data just in case.

You could also try to just use the minimal components and add until the temp gets too high--exposing the culprit.