Audiovox PPC-6600 / PPC-6601 / XV6600 (HTC Harrier)

i've never owned a pda/phone before, but my new job is all on-site computer repairs, so my question to the people that already own this phone is this - can you use a gps program on the phone with its built in gps reciever to use it to navigate you to your next destination? similiar to the dashmount $1200 units. this wont be the main reason for buying the phone, but rather email and scheduling are the main draw, however if it could double as a navigation unit that would really make it worth the $550 that i've seen it advertised for.