You need the Component Video connection to view HDTV in 720p or 1080i formats though you can still watch HD programming via S-Vid though the resolution will be down graded and aspect ratio reduced. You can also watch standard DTV via component video and the receiver will up convert to 720p or 1080i, however up converted DTV looks pretty awfull and why most people choose to have both component video and S-Vid connections to the receiver for these reasons.