Well, since no AA and 8x AF is the setting for the Doom3 Benchmark (107.9fps) and no AA and no AF for Q4 (61.0) i think it is still pretty comparable.
Also there are cards with 256 MB RAM performing around 100 fps in Ultra Quality (GF 7800 GT, 7800GTX).
Concerning gameplay i think 61 fps sounds fine but considering this to be the average framerate it is just too little.
I tested a x850pro agp with an Athlon 64 3200+ and had an average framerate of 71 fps in Doom 3 (1024x768 high Quality, no AA, no AF)
So entering the first lvl it was all smooth when exploring the base (60 fps) but when encountering two or more fast guards (not the zombies) the framerate dropped below 30 fps. And this is when it really counts imo.
So im hoping the 7800 GS wont fall below let´s say 40 fps (or whatever is still smooth, 30 fps for sure is bumpy) even and especially when it comes to lively action.