I was kind of in the same boat, although once I got 'eyeshine' the game started to get much better. My biggest complaint is the engine. I have to crank things down to 640x480 to get a reasonable framerate with antialiasing.
The deal with the video settings and getting a good framerate is to do with the pixel shader setting. Select 2.0 or lower.
DO NOT select the 2.0++. Athlon 64 FX-53 and 6800 GT 256mb and it played like crap with 2.0++ at 1280x1024...but if you drop it to 2.0 it plays fantastic, and in alot of ways looks better than Doom 3.
Personally I prefer nice textures with slight Bump Mapping rather than the D3 method of bump map everything to give flat walls shape.
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Zero Tolerance Games Counter-Strike: Source server.
http://www.ztgames.com