adv.& disadv of DOS, WIN 3.1X / Win95

I am tutoring a group of students re : Windows 95 foundation. I would appreciate if someone could furnish me some information (web Link) in relation to advantages & disadvantages of DOS, WIN 3.1X & Win 95. I have my lecture notes but I would liketo give more to my students. Is there any place I can get some diagrammatic illustrations of the same.

cheers