Check out this place for parts. I'd just go with a good jamma board with a switcher so you can use your xbox or other system.
http://www.jammaboards.com/
Keep in mind whether you want mostly vertical or horizontal games as that will determine which way you mount your monitor and which game board you get. Mine is a vertical 48 game multicade with a 27" monitor.
They are very, very heavy so, make sure you put heavy-duty wheels with brakes under it so you can move it around easier!