These free charts for inland waterways <http://www.tec.army.mil/echarts/inlandnav/> work with MacENC <http://www.gpsnavx.com/MacENC/index.php?page=Features> The easiest way to connect a GPS to a laptop is to use a USB model like that offered by USGlobalSat.. USGlobalSat BU-353 USB Waterproof GPS <http://www.usglobalsat.com/custom.asp?recid=7> John --