Linux for Tots?

ecliptik asks: "My mother works at a nursery school and she asked me to setup some old 486's that had been donated for the children. I figured this would be an excellent scenario for Linux since it wouldn't cost anything to set up. My dilemma is, how exactly should I accomplish this? Anyone have any suggestions for distros to use, maybe some open software that would be good for kids ages 4 to 7?"