Thank you for the pointers.
Reading the wm2005 stuff, and even allowing for any forum getting mostly negative feedback, there seem to be many compatibility issues with wm2005, especially if using software that was wm2003 or (in many cases) pre-wm2003.
I have stopped using PDAs for anything half serious anyway, but the 4700 is handy for checking email and doing quick replies. And for getting TAFs/METARs for flying.
Is there a 640x480 PDA with WIFI, GPS, GSM/GPRS?