Advent netbook with XP OS running NavBox Pro and a 3 Data dongle for mobile broadband access when there is no suitable Wi-Fi. I also have a 12v DC to 240v converter so I can power from the car if the battery runs out.
I find this set-up very handy for flight planning on the move. For me a good portable printer to get hard copy of the flight planning documentation would be more useful than the smaller form factor of a smart phone.