Disclosed is a portable navigation and communication system. In one embodiment, the system combines within a single enclosure a GPS satellite-positioning unit, a means of mobile telephony using cell phone technology and a means of personal computing capable of wired or wireless internet/intranet access using a standard operating system. In one aspect of this embodiment, multiple displays can maintain functional independence of simultaneous operations and allow for fail-over to enhance reliability. Further, a speech recognition subsystem can also be included to provide a voice-activated, speech-controlled user interface for hands-free operation.