when you do use the usb gps, you may find your computer decides to see it as a microsoft ballpoint mouse from time to time, with the result that the cursor jumps all over the screen. Most people wait until windows is loaded then plug the mouse in which aviods the problem. This suits a laptop and dongle well. If you are going for something more permanent as i did - a fixed marine pc, then this can be a pain if you wish to leave an externally mounted usb gps permanently set up. Fear not there is a fix, something you do in the registry, its a bit beyond me computer wise but if you google it there are some clear instructions on how to stop windows from doing this. you basically set a value of zero to tghe ms ballpoint mouse and it makes the problem go away.