the regular sa8300 has a sata port that you can can connect an external hd to to add extra storage space to. This particular model is for cable compaines to comply with the new fcc ruling that by I believe July 1, 07 that the encryption as to be separate from the box. So customers can purchase their own box and rent a cablecard to plugin to the box and get all of the vod features. However last time I heard thier were 7 or 8 cable compaines that got exemptions from that date, Cablevision being one of them they have until July 1, 09. Comcast, Time Warner and Charter have not been granted the exemption.