The biggest effect on gaming quality in a flat panel display is not necessarily DVI vs VGA input, but rather refresh rate.
Ideally, the flat panel should have a refresh rate (total) of 25ms or less for a game like AH. Planar makes some very nice ones that refresh rather quickly.
Over 25ms you will have ghosting of the image whether or not you use DVI. I will agree, though, that the DVI output seems to make the image much brighter and sharper than VGA (from the same card, an nVidia Quadro4 Pro GL).
Most modern graphics cards provide DVI capability. The Radeon 9600 Pro with 128 MB is an outstanding dual output card for under 200 bucks.