http://developer.webtv.net/tools/viewer/

WebTV Viewer Tool

    Note The Windows version of the WebTV Viewer now has PAL support (European
    broadcast standard) in addition to NTSC support (North America and Japan). See the online
    Viewer Guide for details.

    Preview your sites on WebTV without leaving your PC! The WebTV Viewer
    simulates WebTV on your personal computer. Read the online Viewer Guide to
    find out more how to use this software, or go directly to the system requirements. 

    Note The WebTV Viewer program is currently beta-level software on both
    Windows and Macintosh. This means that it has not been completely tested and
    debugged. We provide this software in order for web developers to test their
    pages.