I'm getting ready to plunk down some cash for a new TV. Which one of these guys should I buy? Here are the differences according to Panny's website. 56TWD63 vs 56TW53 1. - 540P/1080I vs 480P/1080I 2. - HDMI vs DVI-HDCP 3. - AC3output vs none 4. - Cable card vs none 5. - Built in HDTV tuner Do the above conditions warrant spending the extra $400? Also can someone explain to me the 540P? I thought everything was 480 or 720 or 1080. One last thing, I heard that even with the built in tuner, I may not receive channels in HD because of incompatibility or something like that?