Never heard of the Lego WeDo. They seem new, and pretty cool, albeit pretty limited. The nice things about the MindStorms is that they are very flexible— you c

Never heard of the Lego WeDo. They seem new, and pretty cool, albeit pretty limited. The nice things about the MindStorms is that they are very flexible— you can build simplistic project (a basic 4 wheel car that you can program to move around) or extremely advanced projects (people have built rubik's cube solver using mindstorms). If your 5 year old really gets into them, he'll probably use them for years.