remove personal data, keep programs?

I'm selling my computer and the buyer wants to keep my programs. How to I go about removing all my personal data but keeping the software? I recently put leopard on my imac and did an archive and install so all the applications are living in my "previous system". What's the best way to go about this?

 

I will be giving them the cds if thats a concern. Its not anything big like Adobe CS3 or anything if you're worried about that.