Just something else I'd like to add. Mame uses stolen roms and therefore, it should never be setup in a public place, especially in a high school. It not only puts the mame project in danger (If enough mame cabs are found in the public, arcade manufacturers will put the hammer down.) but sets a bad example for your kiddies.
Mind you, they probably woulnd't see anything wrong with it, but aside from starroms, there isn't any legal way to use mame.
Also another oddity is the coin op inudstry. In many communities, the same people that furnish your vending machines also have arcade machine routes. If they catch a running mame cab in your facilities they could be angered and blacklist you, which might get your vending machines removed.
And xbox is a nice, safe, legal way to entertain your kids. On the side of caution, you probably should skip the mame cab.