FYI - the 4ghz is the overclocked speed, it is really a 3.2ghz processor. You really can't buy a native 4ghz processor just yet.
Also, I broke down the prices of the each individual item from their price on Newegg, thought it might help. It's over $150 less than the tiger direct price, and if you are able to snag any sales, it could go lower. (The liquid cooling system was not on newegg, so I just used the google shopping price)
ASUS Sabertooth X58 LGA 1366: $200
i7-960 Quad-Core CPU: $280
12 GB DDR3 1600 ram (6x2) $132
COOLER MASTER HAF 922 Case: $100
750W power supply: $66
CoolIT ECO-120 Cooling system: $60
Total Cost: $838
My 2 cents is that I do think that something almost as effective can be gotten for even cheaper.
Also, there is no such thing as overkill on CPU speed for mame, as long as budget permits. The flipside is that you will never get all mame games to run without problems, no matter how fast your CPU is. At some point trying to get extra cpu will be a fools errand.
Also, as fallacy pointed out, you will need to get a graphics card as well no matter what. The motherboard listed comes with no onboard video, and you would want a graphics card for non-mame emulators anyway.