Does anyone use any GPS software/equipment on their 750? I was thinking about installing a separate kind of GPS reciever in my car, but, since I already have this device, and I know it's got the optional GPS equipment add ons, I thought maybe go that route instead. I know I need the software and receiver. If anyone uses GPS equipment with their 750 and wouldn't mind sharing about it, I'd like to hear from ya. By the way I was wondering if anyone also had a good opinion of the best/worst sellers i.e. Tomtom... Garmin etc. (Which one do you prefer?) Thanks!