Where a mp3 player might be easy to carry around, I would advise against recording in MP3 format. If this is something you plan to do and do right, I'd suggest looking into a reasonably priced portable DAT as well as investing in a few different microphones and possibly booms. An omni-directional for background sounds and probably a powered condenser for getting in close But if you hold the mic in your hand, it'll sound that way. You have to consider sound the same way as picture resolution. If you are using mp3 to start, its like a compressed JPEG. Record in at least cd quality to start because in your movie you can always step down from there to avi audio. Going from mp3 to wav and then possibly to wmv or avi, you'll notice ugly artifacts. Fortunatly as a musician I have all the toys and tools already, but you can find good gear that doesn't cost an arm and a leg. If you invest in a digital multi-track recorder these days, they have all the effects you could hope for all in one box. Check out the Korg D-12, D-16 (and lesser models)