On 1004, almost anything will work now. How WELL it works (h.264 stuff on ui2 with compositing for instance) is where the rubber meets the road.
If I were you... I would see how the onboard works... and if that doesn't suffice... most any nvidia card will do (ok, not something you found in a box from 2002). Some of the latest and greatest nvidia can pose some issues because I am using an experimental driver for a handful of chipsets, and there just aren't enough floating around our little community to work out the finer kinks.
It is hard to answer your question really. Until recently really the ONLY thing that worked well was a bunch of nVidia chipsets. Now... MOST GPUs work well... and they haven't been utilized long enough for people to add to the wiki. MOST people using the system are doing so on known working stuff. I have UI2 alpha running on everything but this little integrated VIA. In the case of one of my ATIs I have to turn off the screensaver for flawless playback. This makes ATI my third choice based on the 3 pieces of equipment I can get my hands/eyes on. nVidia is now my second choice... and Intel is kicking ass and taking names... outside of some sandy bridge stuff.
I recommend doing a 1004 dvd install. It is faster, lighter, less error prone, and MD functionality is embedded. You don't need to run/do anything, just follow the networking requirements, and plug something in. 1004 supports a MUCH wider array of hardware, and is very stable at this point.