Forum Moderators: bakedjake
/usr/X11R6/lib/X11/Cards to get an idea, but any generic/budget video card from the last few years should be fine, or something sure-fire like a cheap ATI Radeon.
There are also open source drivers available for some cards from the DRI Project [dri.freedesktop.org] and Utah-GLX [utah-glx.sourceforge.net] project if you don't wish to use proprietary drivers.
After that it's just deciding how much of a hit your wallet can take.