|There are softwares out there that will do this for you but they cost money. Here is how I did it for my mother in law.|
Export as Datebook (.dba) from Palm Desktop on your PC.
using Yahoo Calendar import the .dba file.
Export the calendar as a .csv file.
Set up a Google Calendar and import the .csv file.
Export as iCal file (.ics) from Google Calendar.
Import the .ics file in iCal.
please note there is probably other easy ways, however I have used this one.
best of luck.