There are now hundreds of contact managers. Over the years I've learned no one can answer which one is best for you. My advice is to try the freebies and move to the paid ones with demos until you find what you want.
http://get-simple.info/ looks to be free, has a forum but I fear a non-computer user may be upset about it's 5 minute setup.
I work in Sales and I've tried endless demo's of these Sales CRM software, however none of them are really any good for what I want and they're all too complicated.
Basically all I want is something where I can input a contact & their details (all my own fields) then simply be able to track each customer via each interaction we have. I have 500+ customers and all buy at different part of the year, so far I havn't seen anything which does this. Been using OneNote as a online Diary type system so far, but sometimes contacts are forgotten.