MP3 player and music archival for travelling

I'm getting myself really confused. Have you ever tried to work out how to compress an entire music collection into a device the size of a deck of cards so you can travel around the world and have your collection with you?

Here's the situation, we have around 600 CD's in our collection (we actually got rid of a couple of hundred already, and we can't take cassettes or lp's so these have been put into storage), we constantly buy new music. Ceejay plays the guitar and used to play the violin, and I'm just a music addict, so we need a device that can handle a big collection. Best of all, our collection is diverse. From rock, to techno, to classical, jazz, country, almost anything.

I've been systematically ripping our collection onto my hard drive at 256kbps mp3, using CDEX and the lame ripper with VBR set. I find for my purposes this gives the best quality playback, and when you're listening to classical or jazz you need to hear everything that was on the original recording. Lower bitrates seem to clip parts of the music and lone instruments, like a horn or trumpet can sound a little less sharp.

The dilemma is that I need to fit these all onto an mp3 player (actually 2, since we'll need one each). So far the ipod with the 80gb drive looks the most promising. We need gapless playback (techno/trance and classical tracks don't have 2 second gaps), we also need the ability to search through our tracks, and we need the ability to create playlists. I would also like an eq setting that at least alters the bass and treble, but ideally would like a full equaliser.

But with our collection being so diverse, can any player actually do what we want. Initially I'm thinking we might have to ditch the earplugs and buy a good quality set of headphones, have you ever tried to listen to a mozart concerto or throbbing metallica on the earplugs that come with most mp3 players? I like my volume turned up so distortion is an issue, but also, how good is the software on the ipod? Can it handle a diverse collection and produce rich CD quality output? Finally, how stable is the hard drive in an ipod, and are tracks set to read only so they can't be accidentally deleted. I know that our music collection is going to take up a lot of data-dvd's, and I don't want to have to reload them once they're on the player. Are there any other players with big harddrives?