once upon a time, amd had something that gave it a tremendous advantage over intel and that was the memory latency speeds. since they had an integrated memory controller on the cpu, that was quicker. but not with the nehalem processors/systems you can compare apples to apples.
The Intel 1U and 2U servers SR1600UR and SR2600UR family barebone systems are quite nice in that they have very good upgradability and hardware based remote manageability. The systems support (currently) a total of 96GB of memory (half per processor) use DDR3 memory (both server and desktop memory supported).
It will give you the option to start out with one processor and a few gigs of memory, then in the future you have the option to do a fast upgrade to dual processor and more memory.
as you said, its hard to find numbers for gaming server benchmarks. these usually have to be interpreted from floating point operatings and memory bandwitdth.