Using two monitors on one card may be slightly faster than a pair of cards with one monitor per card, but I've not really done any tests to confirm that. Either way, you're only going to get OpenGL on one screen, unless you go with a high-end professional card. One thing though, if you plan to use Windows 2000 Pro, you should go with two separate cards, because it has a "feature" that prevents most dual-output single-card setups from seeing each monitor individually. This means that (afaik) you can't have separate resolution settings on each monitor, and it messes up some programs like Powerpoint that like to be able to see and distinguish each display separately. Windows XP does not suffer from this "feature," fortunately.