I use a Garmin GPS 10X receiver, with Garmin Mobile® XT software and a bluetooth headset.
My iPAQ210 connects via bluetooth to both the Garmin receiver and headset.. It works great!
I bought my iPAQ 210 and Garmin products as a package from HP.
I use the Bluetooth headset because the volume from the 210 is a bit low. Generally I can hear it from the 210, with the headset I can always hear it.
See the links for Garmin products:
https://buy.garmin.com/shop/shop.do?cID=158&pID=423
https://buy.garmin.com/shop/shop.do?cID=138&pID=11413
Mark