Portable DVD question

I bought a 8" portable DVD today for road trips with the kids. Very cool unit. It came with 2 headphone sets and has built in speakers. The built in speakers are nothing to write home about. My question is this:
What are some good external speakers to use for portable DVD players? Also, does anyone know of a good adapter for the car so I can play it through the car speakers? My cage has a nice Bose system and the movies would sound great. Anyone?

There are cables that have the little headphone jack on one end and the red and white AV plugs on the other. If you had an aftermarket headunit with and input option you could use that. Assuming you have the stock headunit and no inputs I think you might be stuck. Look into an FM modulator. I know they make them for CD changers...don't know if you can get a generic one with inputs on it. Basically it connects inline with your antenna and then you tune your radio to an FM station that you set on the modulator, the sound comes over the radio.