oh yeah.. if anyone wants to know where i got the poster.... I made the image in photoshop and then uploaded it to cafepress and then bought it.
As for the cinderblock walls... the sound is great... I don't get any echoing or anything like that if your wondering.... The room itself is about 12 feet x 20 feet.
The way i layed it out is half is like my office and the other half is my home theater setup.