Pocket Internet Exploder
in my experience is very limited compared to what the desktop version can do. Chances are, any websites "IE Only" which wont work in the likes of Firefox on the desktop, wont work on Pocket IE either.
Word, Excel etc are also limited by the fact you will be using a stylus to input, either by handwriting recognition (not always accurate) or on-screen keyboard (slow, small).
Have you looked at any of the supermini laptops? Or perhaps something like the
OQO - a device not much larger than a PDA, which runs a full Windows XP. It is slightly expensive for the specification however and unless you use a USB keyboard or "docking" station, you still face stylus input or the fiddly-looking pop out keyboard.