Toolman

PDA
A PDA could help John by organising all his existing paperwork into one hand held device. The PDA would hold everything from his contacts to his schedule and contact information. The advantage of John sticking to his old paper system is that he is less likely to lose a big stack of paper than a small PDA.

GPS
A GPS could help John because it would mean he wouldn’t have to carry around road atlases and it would be easier fro him to locate new clients. The disadvantage of GPS is that sometimes it can become confused with road layouts especially when followed without the aid of prior knowledge or a roadmap.

Laptop
A laptop could be used much the same as a PDA in that it could be used to store all the paperwork John already has. The disadvantage is a laptop is more likely to be stolen or damaged than a stack of paper.

Mobile
The advantages of John having a mobile phone are pretty great, the main been in the long run it will probably cost him less to have mobile rather than making calls from public phones. It will also mean John would travel lighter because he doesn’t have to carry all the looses change.