DTV uses KA band satellite transponders for most of the HD channels, with the SD channels transmitted from KU band transponders. No one knows at this point, whether DTV will begin using the KU band equipment to send more HD programming. KA frequencies require a completely different LNB than KU. DISH transmits both SD and HD programming using the KU band, so the same LNB can be used for both, requiring only a receiver change if you have an older SD only receiver and DISH ever decides to drop SD.