Microsoft Knowledge Base Article 308162 contains the following summary:

This article provides step-by-step instructions for setting up a Network News Transfer Protocol (NNTP) server on a Windows 2000 Server-based computer.

Microsoft NNTP Service implements NNTP, with which you can create newsgroups and host discussion groups on a server. By using any standard news reader client (such as Microsoft Outlook Express), users in your organization can read articles from others who have similar interests, post articles to other users, and participate in conversation threads.