Copied this from another website:
Games that work
Call of Duty 4: Works really well, good fps gains.
UT3: This works, decent performance gains with CF enabled.
Bioshock: Works Amazing
Medal of Honor Airborne: Minimum 60 fps, one card drops to 35.
Half life 2: All the half life 2 engined games seem to work.
S.T.A.L.K.E.R: Gives an additional 100 fps at all times, sweet.
Gears of War: It works one cards drops to 50 fps in tested area in CF doesnt.
Hellgate London:Cant run DX10 fails with single card and CF. In DX9 mode 70 fps with single card, CF gets 100-120 same area.
Call of Juarez. Only have the DX9 version 60 fps single, 90 fps CF in tested area.
Gothic 3: Works really good.
Oblivion: Seems to work you might need to patch the game.
World of Warcraft: Crazy fps in this game.
and that list hasnt been updated in a while...since like 2007 or something like that