You won't have any bottleneck with a 955 or better quad with gaming. You will have higher CPU usage with a 955 compared to say an I5 760, but still not enough to cause FPS loss really.
Although intel is good/better at gaming, it's other things that intel is better/faster at. Rendering, file compression, encoding, etc.
Why do you think I run mostly I3's and I5 dual cores? Because they aren't a bottleneck in games plus they overclock like crazy so single threaded apps run extremely fast.
I only picked up the I7 870 cuz it was a good deal cheap, $200 shipped.