Ah, a classic case of "HT inertia." I have had it for about 6 months and just this weekend broke out of it. Symptoms include an inability to proceed with the project because of the fear of doing something "wrong" and spending countless hours worrying about whether some extreme technique is worth the extra expense and time. For example, is it worth putting 2 layers of drywall with green glue if you don't want to spend a weekend building boxes to enclose your can lights. What about furring strips? You know if you use furring strips your room just became 1.5" narrower? Now add 2 layers or 1/2" drywall, you just lost another 2". Now linacoustic, 2 more inches gone. Ahhhhhhhhhh!!!!!! No wonder you can't get started!
But, there is help. Start with a thread, a floor plan, and some basic pictures. Read the threads mentioned above. Then read Blackcatt's and the Geek's thread also, because you need a sense of humor when you embark on this journey. Most importantly, realize that even if you wait 10 years to start your project, there are going to be things you mess up, things you wish you would of done, and things you are down right embarrassed about. But at least you can then write a post about it and get ridiculed by your peers. Get off your butt and start building, my man! Your theater awaits you!