i did a similar machine that had a rear projection TV screen a while back... think it was a time crisis or something like that.
anyway, i gutted all the old tv stuff out, built a shelf in the cabinet out of plywood and 2x4's and placed the TV right on it... screwed the base down and made a couple wood supports on the left and right sides so it didn't flop around, and put a new piece of lexan plastic on the front.