Looking for some advice. I currently have a 46" sony HD tv, supports 1080i. Am looking @ replacing it. (I have no feed @ 1080, so am unable to see 1080 vs 720, which is all my current cable, comcast, broadcasts in). I would like to get something in the 47 - 53 inch range, LCD or Plasma. Most of the current models are 720p that are in my price range. Is the pic quality @ 1080i worth $400 vs 720p?