I have a Tivo HD and don't use any HD box from Comcast. But sometime last year Comcast started to charge me $10 "HD Technology Fee". At the time I called CSR and asked why I was charged. I was told that it is a part of their new pricing structure that has nothing to do with whether I rent the HD box or not. I recently noticed a FCC note regarding some related new rules went into effect on Aug 8, 2011 and called Comcast again. They admitted it was a mistake. I got all my money back and free HBO for one year for the "inconvenience"