At the North Lincs meeting I done a quick demo of the Quo mapping system.
Following that Here is a link for the download
http://www.mapyx.com/
It is a free download for the software and OS maps are around £2.00 for download the minimum download is 6 maps but when you download the software and register you receive an e'mail with a 10% discount if you dont download the maps soon after they send you a 25% discount so that means 6 OS maps for around £10.
I think for a free basic mapping system that has lots of capabilities its worth a try.
I wont go into details but give it a try.
You dont need to buy the maps to try the programe it has a demo mode.