Yes, I believe you would have better picture than regular DVDs, even on a non-HD TV.  If nothing else, you should be able to enjoy the richer colors you get from HD.
Of course that doesn't mean it's worth buying into a dead format.  You'll have to figure that one out for yourself.  The only reason I pick up the occasional HD DVD is because I already have the player and enough discs to keep it around.  If I had nothing today, I'm not sure I'd go for it.  But that's me.