Johan, I am using Windows XP Pro SP2, GpsGate v184.108.40.2064, i.Trek M5+, and iogear bluetooth dongle GBU421 using the included WidComm 220.127.116.1100 bluetooth software. I changed from the WIndows Bluetooth Stack because I got a pair of Bluetooth headphones for Christmas, that I wanted to use with my computer, and they are not supported by Windows.
When I try to configure the bluetooth GPS as an input GpsGate finds the GPS device but does not find the SPP Slave Service (the bluetooth GPS Setting panel shows "iBT-GPS" in the Devices column and "Unknown" in the Services column). I can configure the GPS to a com port and make it work but I have to manually connect to the GPS each time. Your documentation says that GpsGate bluetooth GPS setup works with Windows Bluetooth Stack and WidComm/BroadComm Bluetooth Stack.