Whatever you do, DON'T get a Palm M100. I had 2 of those things and they were both S@#T. Even when the batteries were brand new they would always crash and I would lose everything until I could hot sync again, and if I hadn't backed up recently I was screwed.
I ended up getting a Visor Deluxe, and it works great. Even though it has the same OS it has never crashed on me, and the batteries seem to last twice as long as on the palm. The one nice thing about the visor is the is you can get the backup cartridge that plugs into the back.
So if you forget to change the batteries, or if you are on a trip you aren't completely screwed until you get home to hot sync again. I would recommend the visor deluxe, or if you want something faster get the Visor Platinum.
But most importantly, DON'T GET THE M100!