Ipods and mp3 players

I've got it into my head that an mp3 player would be very useful with all of the travelling I do. At the moment I use a Discman and it's fine. But maybe having my whole CD collection in one small box is the way to go. And the players are quite cute. The only thing is that the Ipod is an Apple product and that feels a bit like going over to the Dark Side. But of all the players out there it does seem the best.

Many of my compatriots in the office have Ipods and swear by them. They've been showing me how to do the tunes thing and telling me all about the gadgets you can get with them. even one of my oldest and best friends has one now and "loves it". So maybe there is something in it. But will the battery last long enough (whenever I mention 'battery' people shuffle their feet and look a bit sheepish)? And which one to get? Bigger is better and biggest is best, but does one really need 40Gb? I have a lot of CD's, but I don't think even I could fill that up.

If anyone has any thoughts I'm open to them.