A Palms battery life will last 10-20 times longer than the iPaq, depending on what you are doing with it.
Palm offers a signifigantly larger amount of software than do the PocketPC machines.
Interfacing shouldn't prove to be much of a problem. I'm running Mac OS X, on which I often use the Microsoft office Suite, and all of the program files (Excel, PowerPoint, etc.) transfer directly to my Palm via the DocsToGo program that is bundled with the Palm.
PocketPC handhelds win the multimedia competition hands down (Palms don't have an audible speaker).
All in all, it depends on what you are looking to do with your handheld. I already have two portable computers, and a desktop, so another computer was *not* what I wanted. My Palm m505 fits in my shirt pocket, doesn't cause my pocket to sag, and managers everything I need.