Let me start off by saying: you're definitely not the only one.

I have been experiencing these constant BSoDs since building this machine
and installing Vista. Just from looking around I haven't been able to make
any guesses as to what might be causing the issue; Windows Problem Reports
and Solutions says the issue is nVidia related, but it might also be an issue
with Vista itself. Some people theorize that it is a problem with Creative
X-Fi drivers. So far, I've only been able to determine that SLI is not the
cause of the problem.

What are your specs? Perhaps it's an issue with 64 bit drivers, or the way
Windows' 32-bit subsystem (can't remember the name right now) passes
information to the video cards? Here's my setup:

Windows Vista Ultimate 64-bit (OEM)
Intel Core 2 Duo E6700 2.67GHz
Zalman CNPS-9700NT CPU cooler
4 GB Mushkin XP2-6400 DDR2-800 (2 x 2GB) RAM
BFG 8800 GTX OC2 x 2 (SLI)
Creative X-Fi Elite Pro
PC Power & Cooling Silencer 750 W
Seagate Barracuda 7200.10 500GB
LG DVD 16x R/W