At the end of july I'm looking to get either a q6600 or 6750/6850 (any comments on which one and why?) but anyway I want to overclock a little without significantly changing vcore, just a moderate overclock. I don't know if I need something like a tuniq tower or thermalrite 120 extreme or big typhoon if I'm not trying to overclock as much as possible. At first I was going to get an arctic 7 pro with an 6420 but now I'm wondering if I'm getting a faster chip or one with more cores do I need something a lot heavier? It seems like I would for the q6600 but how about for just the 6850 or 6750? Would something like the arctic 7 pro or cooler master hyper tx do me just fine or should I be looking into the heavier coolers?

If you don't mind coolers that weight a lot, cost a lot and can be loud, then the Tuniq Tower, Ultra 120 X, EnzoTech Ultra X and maybe the Thermaltake Big Typhoon VX are currently the top coolers on the market (with the Zalman 9700 LED thrown in for good measure), depending on your system setup.

If you plan to leave the voltage alone or at least not go crazy with it, then my suggestion would be the Scythe Mine. It's quite a bit lighter than any of the above, quite a bit less expensive, quite a bit quieter at full blast with the default fan and still performs wthin a few C of them, according to various reviews (here and here are a few).

There is further/similar discussion, along with a list of best prices in this thread.