I'm looking for advice (prefer link to good reviews) of PDA(s) that
have the following abilities
a) can be easily linked to a Windows XP computer so as to
automatically be updated or update data on the computer
b) works with Microsoft Excel files
c) the Excel file can be changed on the PDA, and when relinked to the
computer, updates the spreadsheet on the computer
d) has a typewriter type keypaid for typing in, and a decently large
enough screen so the spreadsheet can be seen

For your linking and excel compatibility, PDAs running pocketpc 2002 /
2003 are your best bet - however, if your excel spreadsheets have
macros in, then these cannot run under pocketpc. As for the keyboard,
the only iPaq with an embedded one is the iPaq 4350 (although I stand
ready to be corrected on this). Hope this helps with your conundrum.