I have Core 2 Duo @ 2.6Ghz and 7600GT (Overclocked to 640/740). The bottleneck is the graphics card. CPU doesn't have much to do in LFS. I also did some experiments with AA: 0x - 134 fps, 2x - 132 fps, 4x - 112 fps and finally 8xS - 57 fps. Someone said that he has 8600 and uses 8x AA - that is really killing the GPU. 8600 is too slow for 8x AA, there's no denying it. 
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