I can't say, and I was also one who didn't think I noticed any difference between regular and HD tv, but now that I have a new HDTV, and an old one in my bedroom, I defintely can tell the difference. I can also tell on my tv when I go from the "regular" to HD channel. I couldn't at first, but now I do notice the difference.
I still have my first DVD player, which must be 10+ years old. I'm not a big movie watcher; just don't ahve time, so I'm sticking with what I have, until this one dies. At that point, I might upgrade to a blu-ray, but for now I'm happy wiht what I have.