I believe that my video card woes have finally come to an end. As I discussed, the key ended up being my RAM, and not the cards. Ultimately, I guess I can't use 4GB RAM + 2 video cards on Vista 64-bit. This is good to know since I have 4GB RAM installed at home too, but only a single card (for now).
After dropping my RAM down to 3GB, the displays look great, but I kept getting messages stating, nvlddmkm stopped responding. This is the video driver for the nVidia cards. I saw this a lot when I'd lock my screen and then log back in. But occasionally, the display would just lock up for about 10 seconds, then go black, and ultimately come back with the error message. Everything would work again after that. But lockups are unacceptable though.
This morning, I took my nVidia cards back out, and I put the VisionTek cards back in. These are identical PCI cards. These cards are working perfectly after grabbing the latest drivers (released a couple of weeks ago).
Final analysis:
- Don't try using 4GB RAM + 2 graphics cards. Scott Hanselman's/Jeff Atwood's Ultimate Developer Rig is pulling this off; maybe it's because both graphics cards are PCI-Express, I don't know.
- nVidia still has some issues with the driver on Vista (possibly just 64-bit).
- Two PCI ATI cards are working, despite what I found looking at Vista's multi-monitor support.
- It's great to be back to 3 monitors. It's a shame I had to sacrifice a stick of RAM to get there though.