Like I have been posting everywhere, I reccomend the Hughes HTL-HD. It's cheap on eBay, is a former DirecTV Satellite Box but doesn't require Satelitte service (or access card) to work, and has an ATSC tuner, though it doesn't have QAM. QAM is similar to ATSC. Think of QAM as the cable version of ATSC, basically digital channels that are free.
Not everyone has the ability to use QAM though, because for it to work, you must have a coaxial cable installed in your house by your local cable company. If you cancelled your cable service with them, but you still have the cable in your house, it may or may not work on your TV. People prefer QAM to ATSC because they don't have to deal with the hassles of possibly getting poor reception with an antenna.
Getting over-the-air digital channels with the ATSC tuner might be a hassle in that you may or may not have to play around with the antenna to get reception, but the picture quality tends to be better on ATSC than QAM, since ATSC uses less compression, to my understanding. ATSC also has more liberal requirments: simply an antenna, whereas QAM requires an installed active cable connection in your home (note: your QAM cable connection may still be active even if you don't subscribe to your local cableco any longer).
Hope this helps.