for the most part, resolution has a rather small impact on the overall fps by itself. what affects fps most though, are a few of the 'optional' detail settings (even if your resolution is set to a minimum), first and foremost being shader level, and seconded by texture, shadow, and AA levels. if the appropriate settings are set, youll probably near/exceed 100fps @ 1900x1200.
really though, 1900x1200 is perfectly playable, as long as youre careful with which detail settings you opt to use.
i was able to play at 2560x1024 (2*19") with my 7800GT (at above 20fps), as long as i made the appropriate visual sacrifices.