Do yourself a favor and get a board that has dual DVI connectors, not just a DVI + VGA, with some stupid VGA->DVI dongle.
I'm currently running dual 19" LCDs via DVI on both, but on two separate, mediocre cards (AGP+PCI NVIDIA FX5200). It works, but in X, there's often "sparkly" pixels on the PCI-driven screen, and I've yet to find a solution. Another problem is, either due to differences in the chemical makeup of the screens (identical, but bought at different times), or differences in the hardware on the boards, the colors don't quite match (under BOTH Linux & Windows)
If you are running Linux or ever plan on running it, I'd suggest getting a NVIDIA board with dual DVI (5700 Ultra iirc-- some models have dual dvi-- have to look closely), as the drivers for the other manufacturers don't seem as "complete", especially when it comes to "fancy" features like multi-mon, tweaks, etc...