The Comcast box is needed becasue Comcast encrypts all channels above Limited/Basic (the ones that you are able to receive with your TV's QAM tuner). Comcast is also trying to make your TV's QAM tuner completely useless by getting the FCC to allow them to encrypt Limited/Basic channels as well. After getting a Comcast box to see the channels in you Digital Started service package you will need to come up with a way to feed both the box converted channels and the raw cable to your TV to keep the HD versions of your Local channels.
