Getting lost! The Wessex way (Suggestions for navigators?)

I wonder if anyone can help me with this.

One of my favorite places for getting lost is somewhere in Kent, carrying 2 laptops and a handheld, travelling between Cliffe and Higham train station often means that without the right driver, I get lost in the Kentish country side. (either that or I would get lost in the centre of Strood!
Anyway, I am not interested in GPS devices, I have seen one and it didn't work in Higham! I can read a map, I can locate myself quickly, but does anyone know of any software which I can just bung on a 256mb USB stick with the maps of the entire UK? Preferbly around Southern England. The problem is that the device is going to end up most of its time off line, so WiFi is out (plus on the meetups, there is no WiFi point.). I'd be particulary interested if it is for HPC Pro, rather than 2000 as most of my devices are Pro devices.

Pocket Streets maybe. It has a good 50+ maps of the UK. I haven't gotten to try it yet but I will be soon