Does anyone know if I can log data from a handheld garmin GPS, 'on the fly', to a laptop, using the data cable? I need it to feed into some non garmin software to give me Lat/Lon data. I know it will go into Mapsource, but this isnt what im looking for.

For example, with a marine GPS such as the Garmin 720s, you are given auxilary outputs which can be crimped into a serial port and you can use the options menu to switch on different data sets to send.