Depends partly on the equipment you can get for your booth. And how many monitors it needs to show on at once.
In the few shows we have done I have done a couple different things.
1.) Use a laptop and loop it from Quicktime.
2.) Author a DVD which self-loops.
3.) Use a DVD player which allows you to loop specific timecodes.
DVD will probably be the least worry once on show site, since running from a computer you always have to worry about screensavers, sleep settings, and background programs which might be running. But if you burn to DVD you will be compressing for a Standard definition screen, while your image might begin as something larger than 720×480.