With the top and bottom are sealed off (with some holes for venting heat), I wanted to make sure the CPU fan had a fresh supply of cool air so I cut out a hole in the back. I didn't have one of those circular cutters handy so I had to freehand the hole with a jigsaw so I still need to sand it in to something smoother. I also didn't want to make the chassis an extra inch thicker to accommodate the retail box fan that came with the CPU. To minimize cable clutter, I used 1 foot long power cords plugged into a power strip. That strip also comes in handy for plugging in lots of other things.
For more details, see George Ou's Real World IT blog