HardOCP have an interesting forum thread investigating how HL2 may potentially be detecting GeForce FX cards and crippling the game. A temporary workaround is detailed which will be most useful to owners to those struggling to play the game optimally. First (before I explain how this is relevant to the "video card" thread), guess what graphics card this is rendered on? It's not my pic (I'm just hosting at the moment). Do pay attention to the FPS counter in the lower right.

Half-Life 2 'designed' to be crippled on GeForceFX cards?