System randomly BSOD's and restarts

Updated: 2-04 10:10

Question/Problem
About 4 months ago, I built a new computer. For a month, it ran perfectly fine, then it started acting like it does now. I will be gaming, in photoshop, or even in windows in some cases, and the system gives me a BSOD for a brief moment before restarting. In addition... I sometimes get a BSOD before the windows loading screen, and it will even lock up in Safe mode (All I have to know that's happened is a red line at the top of the screen).

During the Holisay season, it ran fine, but the above re-occured after Christmas.

2 weeks ago, I purchased a new Hard drive, and installed Windows fresh onto it. It ran fine til about an hour ago, where the above came up.

I'm not sure if this will help, but here are the specs of my system:
CPU: AMD Athlon 64 x2 3800 Dual Core
CPU Cooling: Zalaman (Can't find the number for the part off hand)
Motherboard: Mach Speed MSNV-939
Ram: 2gb (2x 1gb) DDR Dual Channel
Video Card: EVGA GeForce 8600 GT, 512mb DDR2, PCI-E X16
Hard Drive: Segate Baracuda, 500gb, 7200 RPM, 16mb Buffer, SATA 2.0
Optical Drive: NEC 8x DVD-RW/CD-RW, IDE 133

Operating System: Windows XP, Service pack 2

Web Browser and VERSION: Firefox 2.0.0.11

Your level of experience: Advanced

Duration of problem: Around 4 months now

Any steps you've taken to troubleshoot?
*Checking all physical connections inside the system.
*Unplugging and plugging all components and connections back in, powering on the system after each one.
*Changing the power cable that goes to the PSU.
*Changing and removing the surge protector the system is attached to.
*Changing the wall outlet the system and surge protector are plugged into.
*Physically changing the locations of the DIMM's (I have 2x 1gb sticks, and have tried DIMM1/DIMM2 and DIMM1/DIMM3. The motheboard manual doesn't advise the dimm DIMM1/DIMM2 setup for stability).
*Removing 1 DIMM from the system for a time.
*Various BIOS changes (Main ones being RAM clock speed and CPU Spreads. Some changes lock up the system)
*Clearing the CMOS
*Running CHKDISK /F via Safe mode and Command Prompt (No effect. Continues to report errors. Has locked up while checking in the past).
*Running programs to clean the registry and installer temp directories (CCleaner and EasyCleaner).
*Running Anti-Spyware programs (AdAware SE)
*Replacing the Hard Drive.
*Changing/Updating various system drivers (Video, NForce, CPU).
*Formatting and Re-installing windows (Effect of this mentioned above).
*Using MSCONFIG to eliminate unneeded/unrecognised startup items.
*Checking System Information for IRQ conflicts. (Based on another users comment on the Network Controller conflicting with the video card. Network controller isn't listed under IRQ sharing).
*Removing duplictaed items from the Device manager (All removed duplicates are replaced, or remove other system drivers).

I've checked the System event log, and in all cases of the BSOD... there is no event recorded for it....

There are only a handful of things I can think to try at this point:
*Taking the PSU in to be checked (though I doubt that's the problem, since it runs fine at a friends house).
*Run FIXMBR
*Format and Re-install XP for the third time.
*... go to Vista. If it's hardware related though... this won't help.

Otherwise... the only thing I can think of is something in my computer is failing. It doesn't make sense though, since this system is less than 4 months old, ran fine for the first month, and the one I had before this ran fine for several years before suffering from what this one is doing.

I'm at my wits end here, and am flying in the dark.
Any help or advice would be appreciated.
~NN

Update #1.
BSOD came up while idle in UT3. The error code is 0x0000007E

Looked it up, and it's pointing to the video card. The file nvapu.sys is mentioned on the screen as well. However, the "SYSTEM_THREAD_EXCEPTION_NOT_HANDLED" isn't displayed.

"nvapu.sys - Address B3F2C6F5 base at B3F28000, DateStamp 425d7429"

Based on that, It's either the drivers I'm using, or the card itself. I've ruled out 2 of Micorsoft's options, since A: XP shouldn't be having space problems with 500gb, and B: There are no BIOS updates for this motherboard.

At the moment, I'm using the drivers from Nvidia's site, not EVGA's. Should I see if EVGA has a driver, or call the card faulty?