By the way, if you want to do this the easy way...
http://www.amazon.com/Elite-ZR120WH1-A1080-AcousticPro1080-Material-Projectors/dp/B003RG067G/ref=sr_1_1?s=electronics&ie=UTF8&qid=1355975248&sr=1-1&keywords=elite+acousticpro1080
http://www.seymourav.com/screens.asp
http://www.smxscreen.com/at-projection-screen-application.html (DIY, what you see on this page isn't as expensive as you think...)
http://www.amazon.com/Elite-ZR120WH1-A1080-AcousticPro1080-Material-Projectors/dp/B003RG067G/ref=sr_1_1?s=electronics&ie=UTF8&qid=1355975248&sr=1-1&keywords=elite+acousticpro1080
http://www.seymourav.com/screens.asp
http://www.smxscreen.com/at-projection-screen-application.html (DIY, what you see on this page isn't as expensive as you think...)