Yes I noticed the exact same thing. Doom 3 is severly held back by your video card. I checked with my athlon at 1.7ghz, then at 2.2ghz, there was 1 or 2 fps difference, barely anything. Then I tried overclocking my graphics card from 300mhz to 360mhz and there was almost a 10fps improvement. I guess it doesnt really need the cpu, because honestly, theres hardly any physics going on in this game. Not like far cry where you can play around with boxes and sharks and stuff :)