Thanks for the feedback, guys.
I agree that it's probably a bit much, but I really want to be able to put this thing in my cabinet and then not have to worry about it.
I will also be doing some other emulation besides MAME, which can use more horsepower. I would like to emulate as much as possible and then I can throw my Xbox, PS2, and Gamecube in there.
Since I have moved over to HDTV, I am considering this my ultimate "original aspect ration" 4:3 system.
Thanks for the feedback, though, I think I'll go ahead and order it.