Following up on what my man Brandon wrote in another thread, if one has an HDTV Digital
Box from the Cable Company (Time Warner in this case), and there are seperate channels for the network shows and the HDTV network shows, i.e. ABC is channel 7 and ABCHD is 1107, does this mean that for non HD broadcasts, ABCHD (1107) is still being broadcast digitally and ABC 7 is an analogue broadcast even though they're going through my digital box? The reason I'm asking is the picture of the non HD broadcast (I can tell by the black bars) still looks a 1000 times better on the ABCHD channel then the ABC Channel?

If the picture on the HD channel is not a complete full screen picture, even if the black bars are relatively minor in dimension, does that mean it is not being broadcast in HD?

Why exactly are not all shows broadcast in HD format? Does it cost alot extra to do so? If not, I don't get it.

Lastly, if you rent a DVD that will not fill up the full screen in "standard format"- what 480i option would you recommend watching on? I think I've been using HD stretch plus. I have about 9 or so options such as expand, stretch, zoom, narrow, etc.