[quote user="StringerBell"]1. By no means is all programming on "HD" channels actually HD.[/quote]
Well, you should find that if it was originally SD, it has been upscaled by the broadcaster to HD, who in theory have more time and processing power to do the job than your telly or Sky box does, but that's not to say it'll be up to the standard of a broadcast that was originally filmed in HD, the silk purse rule applying as it does. Note however that film is inherently an HD medium, so filmed shows have a better source to work with than those using video (provided broadcasters can go back to the original rather than the betamax, which is by no means a given).