Standard definition TV programming has a tendency to look bad on HDTVs, but why? What is it that causes this? Is it the HDTV revealing deficiencies in the signal? or is it some wacky processing on the HDTV? Some standard def stations can look OK, such as HBO stations, but generally, any SD content on my HDTV is far inferior to that on 2001 model Panasonic 27" sdtv. What's going on here?