In gaming, the X4 955/965 will be comparable in gaming only performance. It is the rest of the system you'll see a difference with the i7 960. The benefit with going with the X4 955 & ASRock 870 Extreme, is they will match or be close in performance for the cost of the Intel CPU alone. You can use the money saved on going DDR3 tripple channel & X58 MOBO to upgrade other components (if need be or pocket the cash ).
There is no AMD processor that comes close to performing as fast as the i7-960 although the yet to be released Bulldozer may do so. However if you are only using your computer for games then you will not notice much difference between the AMD Phenom and the i7. Save your money and buy an AMD processor and spend the difference on a better graphics card. That combination give you the best frame rate for the buck.