krazie, I consulted a good buddy who is far more knowledgeable than I, and this is what he has to say (edited slightly for clarity):
My ideas (well, my only idea): he flashed the BIOS and the OS probably had to reload the "new" components that it thought were new but it was only a BIOS flash that unlocked a few things. Since the OS didn't recognize the new hardware it kept BSODing. If his machine kept crashing/locking up then eventually that was going to lead to data corruption which it probably has already occurred
So basically he thinks that the BIOS flash caused the OS to not recognize your hardware, because the new BIOS now is presenting "new" features that the OS doesn't recognize. Windows freaks out, and this is what's causing the restart loop you're now witnessing.
As far as what remedy to prescribe, well... unfortunately, it seems to me that the only recourse left is to start over. A total OS re-installation will hopefully mitigate against the problem revealing itself in the future.
Hope this helps you, and good luck.

CPU Opteron 170 (naked LCB9E 0704TPMW) |
Motherboard ASUS A8N32-SLI Deluxe |
Memory 2x 1GB Mushkin Redline XP4000 DDR500 |
Graphics Card VisionTek Radeon HD 4870 |
Hard Drive 2 x 500GB Western Digital WD5000AAKS |
Sound Card Auzentech X-Fi Prelude 7.1 |
Power Supply PC Power & Cooling Silencer 750 Quad (Black) |
Case Silverstone SSTJ09B-W |
CPU cooling TR SI-128SE + Scythe Ultra Kaze 3000 rpm |
GPU cooling ATI Reference Cooler |
OS Windows XP Home SP2 |
Monitor Acer X193+WD |