I think most original cabs didn't use more than a 19 inch. What type of monitor you use really depends on your goal. Do you plan to play pc games on it as well? Do you want to run consoles on it, or just emulators? Do you want the "arcade perfect" experience. My preference for monitors runs like so: Multi-sync arcade monitor, standard arcade monitor, standard TV with S-video, computer monitor. That is just my opinion though. An arcade monitor is going to cost the most, so that is a consideration for most people. Tvs are cheap because a lot of people have one lying around somewhere, ditto for computer monitors.