It is an "unfair" comparsion for me. A Q6600 is a good (and cheap) CPU. From what I read it is possible to overclock this CPU with ~3GHz or a little bit more. For this reason you could have the same CPU speed of your OC E6300 with 4 cores.
The i7 is a complete new architecture. All 4 cores are on one silicon die and not seperated on two dies with two cores each. At the moment the price for RAM and mainboard is too high. The i7 architecture is very interesting and will be the future, that is clear, but at the moment it is better getting a Q9550 or 9650 (the prices dropped a few days ago!) with the needed amount of RAM for less money. And a Q9x50 system is also fast and much cheaper.
In a few month it may have changed and the prices for the components are on a more reasonable level.
I saw only comparsions between Phenom/ C2Q and the i7 and the lower clocked i7 were mostly a little bit faster than the C2Q.
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