Hey,
The hip hop act I produce played live once in a bar, here's how we set it up:
1. I made mixes of our tracks without vocals and some of the synth parts, burned them to cd, and played them on a cd player through the stage mixer.
2. I brought up a few synths with me for show and played some of the parts missing from the cd mix, these were routed into the stage mixer.
3. The rappers had mics and rapped over the music as it played, they were sent into the stage mixer.
4. The stage mixer main outs were sent to the house mixer and through the house system.
Dats are nice because they don't skip; however, they're more expensive than cd players, dat tapes are more expensive than cdr's, and not all house systems have dat players...i'm sure that ALL house systems have at least one cd player. If you bring a portable cd player, a lot of them have electronic skip protection which means you won't have too many skipping problems if the house bass shakes it up a little.
Minidisc is another option, and they're pretty cheap.
And whatever you do, BRING A BACKUP COPY OF YOUR MUSIC!!!! Otherwise you're screwed if your only copy gets ashed on or scratched...
Take care,
Nick