I have a house that was wired for cable and subsequently had another coax cable run to 2 rooms with DVRs. I now have an HDTV in a room with a wall that could only have one coax cable jack. I would like to upgrade to SWM to get HD and an HD DVR to that TV. Do I have to run all new cable or can the existing cable be used for all rooms. I have a powered multiswitch that I know would be replaced by the SWM 8. Is this possible? Do I call DTV to have this done or a local DTV retailer?