What I have done is configure a COM port using WinEvent to capture my GPS data. You will have to write a configuration routine, store the COM port Baud rates, etc, and read that data in to init the COM port. Then I listen in my timer. I look for the $GPRMS in my incoming stream (This has the Lat, Long, Speed, Direction) and then wait for the ending <10> char, at which point I pass the string to a routine to parse the $GPRMS NEMA sentence, and do what ever, display, transmit (via Nettalk) the data.
I hope that helps some.
Paul Crafton