Topic. Specifically Fallout New Vegas. I have to run the game by running a famous 4GB hack called 4gbfnv.exe (and also a fullscreen hack called Fallout_fullscreen.exe). This prevents my current 6990 from being able to force AA or supersampling on the game. Would definitely rather know how well forced-AA (or whatever) works with Nvidia cards before forking over hundreds of dollars.
FXAA is a post processing filter, and can thus be used on any 3D application regardless of whether or not it is internally supported. However, on applications that do not support it natively it will also anti-alias the overlay, which may cause the UI to appear blurry.