Hi Tom,
I've heard varying methods to determine optimal viewing distance. I'm not sure about this, but it may also depend on the type of TV you have (16:9 vs. 4:3). I've heard the seating distance should be two to three times the diagonal length of the screen, but I've also heard twice the height of the picture.
Perhaps others will be able to provide a more definitive answer to your question.
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Scott
Hey,
I also heard about two or three times the width of your TV,
It's hard to tell with out knowing the size of your TV.
I have a 5' by 9' screen and I'm seated about 11 or 12' away
but that will vary with your screen. I suggest you turn on your TV and sit at different distances until you find the perfect one.