I too, am building a stand for our home theater equipment. In my research into appropriate designs and construction techniques, I have learned a few things. Most of the equipment you will have or get will be heavy, especially if you are using a large screen CRT monitor TV. MDF is good, but as pointed out above, it is difficult to achieve an attractive finish. It also has problems with making strong joints, and will crack if not carefully nailed or screwed. MDF also will sag under a heavy load and will require a lot of bracing and support. I plan to use 3/4 hardwood veneered plywood, which is much stronger and accepts most fastening and jointing methods.

You asked about leaving the back open. This is not good if you are supporting much weight as mentioned above. The back will supply a lot of strength and prevent the cabinet from wanting to rack (twist diagonally). I will be using a 1/4" veneered plywood back, with large ventilation/cable openings routed into the center of it.

To ease the equipment installation, try to work in some opening sides to give access to the cabling or possibly drawer tracks on the equipment shelves. If your TV is to be enclosed in the unit, be sure to allow sufficient depth as well as height and width. Most commercial TV cabinets sold by furniture stores are only 19" deep, the standard dresser depth. Most new CRT TVs need 22 or 24" in depth to prevent the front support edge of the TV from hanging out over the front of the cabinet.

I would be interested in hearing what you finally end up in making. Keep in touch.