Ok, got this solved. Not sure which of these three things did it, but after much research, I decided to try all three at the same time. I should note, that I had already removed my GT430 (which is my 2nd/3rd monitor card).
#1) Removed all programs which might have some sort of display interaction, for example, Team Viewer, WebEx, Display Fusions, Display Link, etc...
#2) Unplugged all drives connected to Marvell Controllers. Found some information on a possible Marvell bug.
#3) Removed all Nvidia drivers through the control panel, then set the GTX680 to use the VGA driver (from device manager)
I rebooted. Then started the installation, and this time it completed. I installed the latest WHQL drivers from Nvidia, then plugged in each drive, one by one, with a reboot after each step. Finally I put the GT430 back in.
W8 is now running. Multi-monitor support is outstanding in W8!
Also, a quick note. The current Nvidia WHQL drivers for W8 (x64), 302.82, have a bug where the drivers will crash when you attempt to shutdown, resulting in a reboot. 304.79 beta fix this issue, as well as several other issues.
