Depends a LOT on the res.

E.x. notebookcheck indicates that FEAR (released a yearish later) could get 20-30ish FPS at 640x480 but chokes at 1024x768 (at numbers matching the HL2 lost coast demo slideshow at 1024x768).

Gotta remember a lot of mac people were just happy to play something more modern than Marathon or Giants CK