Hey man..
Well, there is nothing wrong with the i7 920, and yeah..for the price--it makes the most sense.
Money aside...obviously the 965 extreme chip..
Now, the 940 is expensive...no question...but in a few quick tests I have my 940 running at 3.82Ghz cool and stable and I changed only 1 setting!
Gpu stock, ram stock, less than 1ghz overclock of i7 cpu from stock and I did 18,877 on 3dMark Vantage.
The 920 was a struggle to get stable at 4Ghz without changin' a few things--but it does OC very well ..almost a 1Ghz step up from stock without any volt changes or anything else.
--Take all this with a grain of salt--we literally have been playing around for 3 days and I only got my build up and running late yesterday morn.