My all time favorite movie was "2001 - A Space Odessey". Yeah, I know it came out in '69, so I'm dating myself. I first saw it in the original Cinerama presentation, which was a three dimensional process where the movie was projected onto a curved screen from three projectors at once. The sound was also broadcast in surround stereo, which was a novelty back then. I never thought I'd say a "G rated" movie would be my favorite, but I saw it in the theaters three times, bought the VHS tape twice, and finally got it on DVD.
