I like this calculator better: http://myhometheater.homestead.com/viewingdistancecalculator.html

Yep...and if you are sitting farther away than that your TV is too small. At least if the goal is to turn your living room in to a home theater.

You need to sit pretty close to a 50", 55" or even 60" TV to get the same effect as sitting in the middle of a theater.

I would love to have bought the 70", but my goal was to create the best home theater I could for the money, room constraints, spousal limitations, and etc!

The original question of this topic was whether 720p was a waste of money and I believe that most people don't realize that for most living room applications, 720p is going to provide the same level of performance as 1080p. But those of us who are fans of home theater can't resist the "more is better" syndrome (myself included).

As we all know, resolution is only one factor in picture reproduction. Unless you're looking to have a front projector in your theater set-up (which some people in this forum do!), there are other factors that will affect the performance of a HDTV picture more than whether it is 720P or 1080p.