On the 5500 you are looking at about 2 hours with wifi, and the screen not on it\'s brightest settings.
If you turn the screen off completely with an additional (but free) app then you can play mp3\'s for about 8 hours.
With the screen on full, and wifi, you are looking at about 1 hour.
That\'s one reason why I got a 760 (better battery)
The zaurus however, is not a pda! It is a pocket linux box, and a very capable one too. This power comes at the expense of battery life.
If you just want to keep appointments and phone numbers, then it\'s not for you. If you want a portable machine on which you can write and compile c++ programs, run apache webserver (with php!) play fullscreen movies (the whole movie, not just clips) or even run a mysql database. Then it\'s one of only a handfull of devices capable of doing this in a device so small.
There is even a full debian install for the zaurus.
http://pocketworkstation.org/index.htmlbut the 240x320 display limits this a little. (another reason to go for a c7x0 device, 640x480 display).
Some of these things are hard (for a novice) to get working, you do have to hack a little to reap the rewards. If you are familiar with linux, then this won\'t be a problem, and will enhance your skills and knowledge along the way.
Of course, this forum is here to help you, if you require it.
Welcome to the Zaurus club.
Peter.