The emergence of XML has lead to a change in the development style for Web sites. XML's advantages, such as the separation of content and presentation, or the possibility to develop application specification markup languages, have changed the creation, management and presentation of Web sites. We will investigate the suitability of XML technologies for authoring and delivering virtual, i.e. Web-based, courses. We will include various educational services including lectures, tutorials, and lab sessions in our investigation. In particular, we will consider the development of content, navigation, and interactive elements for virtual courses. Keywords Web-based courses, XML-technologies, e-content authoring and delivery, navigation, interactive services.