I have a Compaq Aero 2100 that I have successfull used both a Haicom 303 CF
GPS with and an old Teletype CF GPS. I think they both ended up on either
Com1 or Com5. I don't have the unit here at the house, so I can't check.
I've used the Teletype with both Windows CE v2.x and after upgrading to
Windows CE v3.

You will need to provide external power as the CF GPS will drain the
internal battery pretty quickly.

John Scott