And a "ln46a550" is (hi ho, off to Google I go...) a Samsung 46" LCD HDTV. According to the specs on Samsung's web site, it has a "clear QAM" tuner. Therefore, if you plug your cable directly into it (no cable box), you should be able to get whatever digital channels (including HD) Comcast does not encrypt in your area. This probably means only the local broadcast channels (NBC, ABC, etc.). For other HD channels, you'll need Comcast's HD box, and you may have to subscribe to an HD tier.