In past posts, this link has been helpful. It is from the internet movie data base (imdb) and summarizes how many movies (DVDs) there are in each aspect ratio. As you can see, most are in full screen, followed by 1.85 to 1, followed by 2.35 to 1. I'm in the same boat you are - about to get a screen in the next month - and I'm going for 1.78 to 1 (aka 16:9) because that's what HDTV is, and it is so close to 1.85 to 1. I'll just suffer a little for the Harry Potters, LOTR, and SW that are in 2.35 to 1...

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Bears, beets, Battlestar Galactica.