PDA/Pocket PC with aviation GPS for European region

Hello all,

I am looking for a PDA that has an aviation GPS to fly in Europe. I
have the impression the US is way ahead of us on these matters but is
there a similar tool out here in the far east (Europe)?? I am new to
PDA technology and until now I learned on the net that you can have a
PDA with Palm OS or a PDA with windows Mobile OS aka a Pocket PC. What
is best, Palm or Pocket PC? Can I buy ANY PDA and install aviation
software afterwards or are aviation PDA's very type specific? For
instance, I have been reading about Apple's iPhone (and similar
devices referred to as "iPhone killers") but would I be able to
install an aviation gps onto it?
Other functions that I would find very useful:
- organiser/calendar
- e-mail
- digital camera
- scientific calculator
- maybe even a phone function???

Handheld GPS's are very useful in the aircraft but once on ground they
become useless. That's why I prefer an all-in-one pocket pc. I just
don't know where to start.

Thanks in advance all for your valuable input!