I can't really comment on the console stuff. For MAME though, it really depends what you want to play. A good 80 - 90% of MAME stuff will run on just about any modern MoBo/processor combo. In fact, most of it will run decently off of a PIII. If you want to maximize your MAME experience and play everything you can though, plan on buying the most CPU you can afford. Even at that, some games (most likely those that use .chd support) will have to be tweaked with frame skipping, etc. to run smoothly.