Which TV is better?
As long as the cable box has an HD tuner you will get the HD picture... BUT the TV still has to be HD ready.
As for which one is better? That is up to personal taste. Personally if I had to choose between those two, I would take the first. But then all the HD and digital stuff does not matter too much to me, as long as I can see my favorite shows :p
Actually, I am not too crazy about the plasma screens. I personally feel the LCD's are a better choice. too many horror stories about the plasma's going out.
Personally I like projectors over TVs. Shame that a HD projector is so much money.