I had the same question before starting school as you did. I am fairly adept at computers, but didn't know a thing about PDAs. In the end, I decided that I would buy a PDA a few months before starting school, and play with it a bit, so I knew how to use.
This turned out to be a fairly successful approach. I found it pretty cool for ICU. The first semester of my program is almost purely didactic, so I haven't had a lot of time to use it clinically yet. But the address book and phone list is very handy. I also use Epocrates a bit for pharmacology. Plus, it's a very nice, although somewhat expensive calculator.
Once I start clinicals, I'm sure it will become increasingly valuable. I'll be putting all the information for my "brain book" on my Palm and also plan to be tracking my cases.
As for recommendations, I bought a Sony Clie as recommended here. Their price hasn't decreased all that much in the last 8 months. The Clie comes with 16 megs of memory, which is very handy and has a colour screen, which you should really get unless your budget makes that absolutely impossible. The SJ30, which I purchased, does not come with a MP3 player, but the SJ33 does. The latest Clie models come with digital cameras and all the bells and whistles, but last I checked ran in the $600+ range.
Your other option of course is the Pocket PCs, which I know nothing about.