720P is probably what you should be using with a 42" LCD, especially considering it's so close to the native resolution of the panel.
People with huge HGTV displays are the ones that need 1080. (>50")
ie: imagine how pixelated the picture would look from 10' if the screen were 10' diagonal; therein lies the need for higher resolutions; BIG DISPLAYS.
The difference on a relatively small 42" HDTV at 8' would be impossible for most people to discern.
IMO, too much emphasis is placed the difference between 720 and 1080.
Wake me up when 2880P is available as an option.