Pocket PC questions

I'm trying to decide between a media player and some kind of pocket pc for my son. I know he'd appreciate being able to watch his movies and listen to music on the portable media player, but it might be even better if he can also access the internet and keep in touch with instant messages and email.

Does anyone know about playing DVD movies on pocket PC's, Or is there a site where I can learn about it? (I don't mean just watching video files). I've read reviews of different models and the buying guide at cnet. I've also read how to get files from a media card to the unit at a site for pockettv (which is a whole nother question for later maybe), but I'm still very confused about a few things.

It doesn't sound like they have hard drives like the media players, so how can they hold files or be used for listening to music or watching movies - just by the media cards? Can he even copy one of his movies to a media card?

And how can the internet be used with them? Who provides that kind of service, and can it be used in the middle of who-knows-where? (he's in the Navy).