These Command Line Switches launches Windows Media Center and cause it to navigate directly to one of the built-in experiences:
%SystemRoot%\ehome\ehshell.exe /directmedia:discplayback - Begins playback of the disc in the drive
%SystemRoot%\ehome\ehshell.exe /homepage:VideoFullscreen.xml /PushStartPage:True - Live TV
%SystemRoot%\ehome\ehshell.exe /homepage:VideoGuide.xml /PushStartPage:True - TV Guide
%SystemRoot%\ehome\ehshell.exe /homepage:RecordedTV.BrowsePage.xml /PushStartPage:True - Recorded TV
%SystemRoot%\ehome\ehshell.exe /homepage:VideoToBeRecorded.xml /PushStartPage:True - Scheduled Recordings
%SystemRoot%\ehome\ehshell.exe /homepage:Radio.BrowsePage.xml /PushStartPage:True - Radio
%SystemRoot%\ehome\ehshell.exe /homepage:Radio.xml - FM Radio
%SystemRoot%\ehome\ehshell.exe /homepage:MusicBrowsePage.xml /PushStartPage:True - Music Library
%SystemRoot%\ehome\ehshell.exe /homepage:VideosBrowsePage.xml /PushStartPage:True - Video Library
%SystemRoot%\ehome\ehshell.exe /homepage:PhotosBrowsePage.xml /PushStartPage:True - Picture Library
%SystemRoot%\ehome\ehshell.exe /homepage:Options.Home.xml /PushStartPage:True - Settings Menu.