Hi, I'm nearly done my first projector (standard 15"), I don't know anything really about cooling and I was just wondering if anyone could help to tell me what they think would be the best way to cool my box. I included some pictures, which are below.

Don't see your pics??
But, I had the standard "dog coffin" box and used the simple 5/8" slot in the top and fan blowing out the back and never had a problem. Straight outa the guide. I only used one fan, but she was oh so powerful!! The key is making sure you are only sucking air from the slot, not from the front of the box as well (the area forward of your front fres).
Does that help?