That's true, the Q6600 is a year older and a bigger die, but even with the lower starting clocks it looks like a lot of people were able to clock to 3ghz pretty easily and even saw up to 3.6Ghz before heat became a real problem.
I kinda doubt Pec0 is wanting to dump a bunch of cash right now. This thread started off with him looking for a good deal for his graphics card upgrade and it seemed a little bit of a stretch to get the card he did. This is why I have been suggesting a budget upgrade for the cpu instead of a whole new setup.
Well that's a switch in generations not just core count that made the big boost in performance for you.
The Q6600 is actually a step back a generation in Core 2's but it's not as big of a difference as the one you made, it will just equate to lesser overclocking ability and more heat production (then a newer quad since quads will always make more heat then dual cores)
OP can you afford to change platforms to something newer with the sale of your CPU, Motherboard and RAM??
I'd prefer not to go down this route purely because of the additional costs involved and more so because we have a baby on the way (due on Sunday), so if anything I'm looking for an easy straight swap of processor.
Looks like he has had them for a while so maybe a good deal can be had.
I couldn't justify going for the Q8 or 9000s thought, they are SO expensive! You can get a new sandy bridge for nearly the same price. I'd go with a budget quad-core here to hold you over for another year or two OR go all out pick up an i5-2500k/3570k and new mobo for about $350.
If you can find something better than the Q6600 for the same price, then go for it, but it looks to me that the Q6600 is the bang for buck option here.