If you have CRT monitors, then don't make the mistake I did. I bought a video card with a DVI and a VGA output, thinking that I could easily use a cheap DVI to VGA adapter to run 2 CRTs. I didn't know much about DVI and ended up with a DVI-D video card. The adapters only work on DVI-I and not on DVI-D. Make sure to look at the pictures to determine which type of DVI the video card uses.
This website has pics that you can compare to. I think that it doesn't matter any if you are using LCDs, since they will use DVI-D cables, which will work with either type of DVI video card.