1. A network system for computer aided instruction, comprising: a main computer including a repository for storing courseware; a network of servers connected to said main computer; a plurality of local area networks, each of said local area networks connected to a server, and each of said local area networks comprising a plurality of interconnected workstations; a distributed delivery system responsive to a request of said server for a course of said courseware, selectively operable to search said network of said servers for said server where said course resides, operable to transfer said course from said server where said course resides, and selectively operable to retrieve said course from said repository if said course cannot be found at said server; an authoring system distributed over a workstation of said workstations, said servers and said main computer, and operable to transfer courses of said courseware from said workstation to said repository; and a course management system distributed over said workstation, said servers and said main computer, and operable to manage course enrollment and to monitor student performance at said servers, and further operable to transfer information corresponding to said course enrollment from said servers to said main computer; wherein said network of servers comprises a first set including said servers connected to said main computer, a second set including said servers connected to other servers and to said main computer, and a third set including said servers connected to said other servers; and wherein said course is in said repository and at said servers.