Remember though, video is only half of the movie.
If you're willing to pay a premium for a relatively unnoticeable change in quality (unless you sit a foot away from your TV) you should also invest in some real HT Speakers.
Don't leaf through your local Best Buy pamphlet and choose the $500 dollar 5.1 HTIB, those rarely deliver.
Instead, invest in some really nice speakers that won't break the bank, but still sound like a $10,000 system.
Here's an example from Axiom Audio, an internet direct speaker company.
Review
This is a great value, as it costs $3681, or about the same as a 1080p HDTV. It also has a mini-fridge sized sub, great for a home theater.
(I'm not a salesman, just letting you in on a good deal)