I am in the same boat, trying to decide on a new TV. I already posted twice and no one responded to my posts. I have been reading a lot of reviews and comments from people who have bought the different models that I am interested in. I am still confused like you are. Sorry I can't help you. Good luck on your decision.
Man, you get a headache trying to decide a on TV! Too much to consider! I feel like I need "Buying a TV for Dummies." I only buy a TV about every 10 years.
I'm leaning toward the 46 or 52 550, 650, 750.
I have cable, satellite, Panasonic home theater, and dvr/vhs combo. I also have a Media Center Laptop that I use as a DVR that I would like to play over the TV.
I watch sports, ESPN (read somewhere about ESPN ticker being blurry on one), movies, regular TV.
So, with those factors, which LCD would be best? How many and what kind of cables do I buy so that everything is hooked up?