Well... The only difference between the 2 are the multipliers. So in OC'ing, the Q6700 can give you a lil boose:
Q6700 is rated 1066FSB (4x266=1066), rated speed (10x266=2.66ghz)
Q6600 is rated 1066FSB(4x266=1066), rated speed (9x266=2.4ghz)
So if you bump the FSB to say 300
300x10= 3ghz
300x9=2.7ghz
So the difference in that speed adjustment, the 6700 is 300mhz faster.
But to match 3.60ghz:
FSB 360 x 10 = 3.60ghz
FSB 400 x 9 = 3.60ghz
When you push the FSB to 400, and your using DDR2800 memory, your actually useing the full advertised speed of DDR2800 memory, while the 6700 would run it slower, but then its easier on the MB. So you do have different pro's con's when you look at the nitty gritty.