What is the best option for a new TV if I have Coax Comcast cable?

In most markets Comcast does provide HD Channels for the major networks on a coax cable. Run the channel setup and see if it identifies any HD Channels. If you live in a major market you will be able to use a digital antenna to pick up HD channels. Depending on your viewing habits, you may want to look at an apple TV, where you can download HD TV shows for $3 per episode. If you only watch just a few select shows, this may be your best option.