Umm, if you mean me,
then the answer to your question is that the USB thingy IS a GPS receiver. It just doesn't have a screen or buttons and stuff which is how it can be powered through the USB cable alone and only uses milliamps.It outputs a standard NMEA 0183 signal that pretty much any charting program will recognize (it was designed specifically for this purpose) through the USB connection.It's about the size of a half-dollar and I think I paid about $70 for mine. It comes with a CD that contains the drivers and instructions.Plug it in and your computer becomes a plotter.Hope that answers your question. If you meant me, that is...