You have to have a cable box capable of picking up high definition channels; there is usually an extra monthly charge associated with that, unless your cable provider is offering some sort of promotional package. The way it works is, you'll get all of your regular channels, and the HD version, if there is one, will be on a separate channel. So you'll get your regular ABC station, for example, in standard defnition, and it should also be on another channel in high definition.
Hope this helps.
