Don't get too caught up with this?
Could be quite a few different things that are playing a factor, if he's running XP and you're running Vista that already gives him a slight performance advantage... Could be a bad driver installation. Either way assuming you use a standard lcd monitor as long as you get a constant 60fps or over I wouldn't even worry about it, measuring how many more frames over what your monitor can display per second is pretty pointless. In other games you will no doubt outperform his machine already.
It is also true that CSS has a cpu bias so you will see improvements by overclocking. I would look into it a bit more, you can achieve a small overclock very fast but to start to squeeze the best out of your cpu will take you time and effort so you have to be prepared to get comfortable with a few things before you can gain an more in depth understanding of how to get a good overclock.
It is more something that takes patience than a vast array of technical knowledge, read the overclocking sticky as suggested. Do you have a g0 stepping q6600? Also is it a recent one? A lot of people seem to have difficulty getting good overclocks out of the recent batches, but you should still be able to see 3-3.2ghz with relative ease.
Personally I am running a q6600 @ 1.4v @ 3.42ghz, I can't seem to get the 3.6 I am after!
Make sure your ram is good enough to support the overclock you are shooting for, with PC6400 (800mhz) you can hit 3.6ghz with a 1:1 ratio (between fsb and ram) assuming your setup will stay stable at this frequency, but even if you do have PC5300 you can overclock to 3ghz quite comfortably. Try raising your fsb to ~333 (you do this in BIOS by hitting the relevent key as suggested).
Don't change values you don't understand as of course you can damage your components (even though it does seem tempting to see what different things do in there!)
Just relax dude and take some time to learn how to overclock. If you are really worried about how your machine is performing, try running some other benchmarks (again check stickies for suggestions, 3d mark etc) and see how you compare to similar setups. If CSS is an anomaly since you already get better than necessary performance, don't worry about it.
Also is he running CSS on the exact same settings, with the same amount of background programs (antivirus etc) at the same resolution? If he has a smaller monitor that already answers this!
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