>Looking at our DVD purchase requirements, what is desired in our family right now are older "Nature" type films, from PBS and BBC, as well as March of the Penguins etc. None of these were shot in HD. Therefore does it make sense to buy their BD versions or would SD ones be just as good? That will decide the player we buy for the time being...
Most commercial films are shot on 35mm film which has a projected resolution (the negatives and early prints have a highe resolution, but release prints are worse and you loose some effective resolution as the film wiggles around while being projected) comparable to 1920x1080 HD.
SD doesn't even compare to 16mm film.