Right now I have a SD TV and am using an antenna for broadcast televison. Picture quality is good but not great. If I were to snag an HDTV receiver I would receive HD broadcast, right? This would then be downconverted to my SD TV set but would it look much better? I will not be buying a HDTV set for a few years as I don't watch enough TV to jusify the cost, but do want to get the best quality when I watch.