amd is lil slower, but way cheaper. ive ran both sides, both sides are awesome.
i have a amd penom II x4 @ 3.5 GHZ WITH 8 Gigs of ram, a 6870 gpu and have no issues running all games on the highest settings.
but im getting a 6970 to make sure!!
edit i love those pasmark links on cpu's, go grab some skyrim benchmarks and battfield 3 benmarks, youll find amd isnt that much slower, ive learned to to those graphs with grain of salt and look at game benchmarks