Strictly gaming without going SLI or crossfire and without overclocking the AMD solution would outperform the Intel i7. You might look at the i7 860/ P55 motherboard to compare Intel and AMD instead of the i7 920 /X58.
jjoven, i5 is not a lot better. It is only slightly better in benchmarking and some applications like WinRAR or video encoding.
However, like many people said, it seems like i5 is another dead end whereas AM3, it is confirmed that you can drop a Thuban (6-core) chip in without a problem. As far as rumours go, Intel's Gulftown is 1336 exclusive. Someone will bound to budge in and start talking about Sandy-bridge and Ivy-bridge, to be released (rumoured) in 2011. Both are entirely new architectures which will most likely require a change of platform (again!). So the choice is yours.