This paper explores the integration of the Windows streaming media technologies into a virtual classroom environment. A set of authoring tools that is suitable for web-based presentation has been developed on the platform of Microsoft Windows Media Service 4.0. Both live streaming and on-demand media productions are supported. For live streaming, a model is presented to implement virtual classrooms presentation of audio and web-based text/graphics material. A user-friendly application was designed to implement real-time media contents play-list control, while another was designed for lecturers to give presentations. Server-side switching is used to achieve switching between the lecture stream and background music/commercial stream. Moreover, scripting command technology is explored to improve the interactivity between the lecturer and the media contents. With a specially designed web pages, the Internet clients can view auto-refreshed slides and lecturer-guided slide highlights, which are synchronize with lecture audio, and interaction with Java Applets running on the web page.