I bought an Archos Jukebox Multimedia player about 18 month ago. It was reviewed somewhere as one of the best techno 'gadgets' to have of the year, can't remember what magazine unfortunately. Basically a 20 gig hard drive that you can store - play/ view mp3, mpeg, jpeg files on. I was only bothered about the mp3 side of things, which it does really well. There wasn't many dedicated mp3 players available at the time so I went for that one and paid quite a lot (about £340) They've come down a lot since then, I would have thought you could pick up a decent dedicated mp3 player for around £200, it'll be considerably cheaper in the States or anywhere else come to think of it...
It'll play mp3s for about 4 hours on a full charge. I've recorded my whole CD collection on 196 kbs (haven't counted but estimate around 350 albums) and a lot of my friends' CDs also. You'll get a lot more albums recording at 128 kbs. It's very stable on the whole, occasionally crashes if it's running low on power. Doesn't jump or crash with knocks, as CD players do, minidisc players can still jump if jarred enough. Can play albums normally or random 'shuffle' songs/ repeat etc. Does quite good recordings if you want to record anything live or 'bootleg' a performance etc. Its about 4"x3"x1.5", quite compact and very sturdy. Good for fitting into a jacket pocket for when you're riding.
There's a lot more mp3 players around now though, think there's some 40 gig drives available. I'd do a search or check some mags out to see what reviews are available.
