At the hardware rewiev section I found:
"NOTICE ABOUT GPS NAVMAN 1000 Navman announce that this GPS isn't compatible with Pocket PC 2003. See at: Navman-GPS 1000"

Four your information:
The Navman 1000 is working OK with earlier versions,
I use it with an iPaQ 3950, Pocket PC 2002 system, works fine.