The school may not require it, but a PDA is the best time planning/info retrieval device ever invented. I started using PDAs about 7 years ago and haven't been without one since. PDA's are so useful that once you start using one you won't know how you lived without it, IF you are the right type of person.
In order for a PDA to be really useful, you must develop two basic habits. You have to put information into it as you acquire it and you have to carry it with you at all times. I have occasionally run into people who tell me they have a PDA that they bought years ago and never really used. After a few questions I usually find that they never developed one or the other of the two habits, especially the carrying habit. If you don't carry it with you EVERYWHERE, you may as well not have it. A PDA requires a couple months of carrying and daily use to become really useful.
As you start to use it you start replacing other things with it. Grocery lists can be stored in HandyShopper (a freebie). You can read some .pda files using the adobe reader for PalmOS. Need a timer to time a lab process or wake you from a power nap during a marathon study session? BigClock. Need a periodic table? ChemTable. Can't remember how to fret a second position Gm7 chord on your guitar? ChordDB. Like to keep up with news? AvantGo. Need a graphing scientific calculator? EasyCalc. Want to know when Saturn rises tomorrow night? AstroInfo. Want an addictive game to waste some time? Bubblet. Need a secure location to store your computer passwords and other private info? KeyRing. Need an incredible Japanese-English-Japanese dictionary? PADict. All of these are FREE, and of course, there are a ton of commercial apps available, too, usually for very low cost.
I favor PalmOS devices (I use a Palm TX), mainly because I hate M$, but there's a ton of useful software available for either flavor. Unfortunately, Palm has gone through several corporate restructurings in the last few years which means the suits that run the place are too worried about keeping their jobs to bother with product development so the OS development has been in a holding pattern. I imagine they have a difficult time hiring and retaining engineers due to all the coroprate shuffling, too. They haven't come out with a new PalmOS based PDA since the TX came out about 4 or 5 years ago. The Treo phones haven't used PalmOS for a couple years. The future of PalmOS is not bright, but it doesn't matter. Your PDA will last you 5 or 6 years if you don't break it or lose it (my last one, a Treo 300 that I got 5 years ago has been retired, still working). In 5 or 6 years you'll want the new one with Gb fiberless optical networking, GPS, and speech recognition. Will it come from Palm? Hmmmm.
I have no experience with pocket PCs running Windoze, but windoze on my desktop computers has been such a problem over the years that I look for ways to avoid anything that involves M$. I can't quit windoze on my desktop computer because some apps are not yet available for Linux, but I don't have to have M$ in my PDA so I don't.
RP