Arrgghh. I removed two disk drives from my hurting ASUS A7N8X-X machine, but I'm stil getting random reboots. Next suspect is memory problems. There are actually quite a few memory testers around:
* "Memtest86":http://www.memtest86.com/. The grand daddy. Now has bootable CD version. Requires 8KB and tests like crazy. Hasn't been updated since 2002 though, so won't detect my Athlon XP 2500+ (Barton)
* "Memtest86+":http://www.memtest.org/. Updated by the folks at x86-secret, this updates memtest86
* "Memtest":http://hcidesign.com/memtest/. Windows-based, so most of Windows actually has to work for this to work, but still useful for the big machines. Like Prime95 or SuperPi, its a way to see if your machine is Ok at the top level. First time I ran the machine hard hung. No BSOD, but seems fine now. Strange errors.