Any pocketPC you can afford.
Something that accepts some sort of GPS reciever
A compact-flash or other variety of GPS reciever
VNC remote control to the PC
Probably WiFi so you can communicate to the PC.
Not attempting to be a complete ***, but for stuff like this, most people around here don't feel like doing your research. For GPS, iGuidance seems to be fairly handy. The rest you just need to figure out...