I use GPS2Blue which is a free app that can transfer the signal via BT or over your cable using a virtual serial port. I have mine set up to transfer the GPS data to the virtual port and then use Streets and Trips on my laptop. Works like a charm.
GPS2Blue:
http://users.skynet.be/hofinger/GPS2Blue.html
Virtual Serial Port (takes a little reading to get the settings correct, but good tutorial on the site):
http://www.hw-group.com/products/hw_vsp/index_en.html