I agree with perrybhadra. If you need HD channels, just plug in your comcast coax cable to TV and use your TV tuner to get the channels. However, you do need ATSC/QAM tuner in your TV which most of the newer HDTV comes by default. Again as perrybhadra mentioned, you will not get all the channels as some channels are encrypted. But you will get over hundreds of free HD channels.