Probably a daft question but are you essentially going to have a mini PC inside the cabinet to run the games or is there some technical witchcraft going on?
No, it's a full sized PC stripped down (won't need a dvd/cd unit and I will try to get as much of the case out as possible to keep the weight down).
You could probably just mount the PC board to the case itself. Isn't that how real arcade machines work?
Indeed, I wonder what the practical minimum PC spec is for this kind of thing? Surely there must be a Linux distribution dedicated to arcade machine emulation? *investigates*
It seems you could even boot AdvanceMAME from a USB key, so a hard drive isn't even nessecary, and it would make getting new games onto the system reasonably practical. You could literally just open it up, unplug the key, plug it into another PC, copy the game across and put it back.