Ok, I just got my new Panasonic AE900, Denon 3805, and Panasonic S77 DVD.
I've got a lot of tinkering to do yet, but I do have the basics set up and I'm finding the picture quality poor. For the screen I have attempted to use a sheet of "Gatorboard" (like foamcore but stiffer) - as is. It is a very smooth (but not glossy) paper-product surface.
Does a projected image prefer a non-smooth surface? I'm wondering if I would instantly get a better result if I painted the board with one of the commonly used high-pigment paints (Behr Silverscreen / Glidden Misty Evening / ScreenGoo).
I have done everything you are thinking about doing. STOP! ;-) I have an 11 foot screen and used Behr Sliverscreen paint. The result was a picture that was "muted" and nothing seemed bright or clear. After 10 months of wanting something better I repainted the screen. I did not do anthing the wall prior to painting (although I did paint the entire wall flat black and later painted with the silverscreen).
First qustions is are you able to use your wall? If you can, paint it flat white. Then get paint called "Screen Goo", that stuff is worth every penny!
Take a look at the pictures under "Home Theater > Bragging Area and the message "It's started, building a new Home Theater" You can even see the difference comparing the paints (they are very small pictures), but I will be happy to email you the full size pictures so you get a better idea of the imporvement.