Once it is assembled, you can start packing it full of goodies.

I was able to comfortably fit a full sized keyboard, a mouse, 50 feet of CAT5, and power cords.  Add a monitor and you are ready to go.

It can also accommodate some fairly large cases.  I used the Sunbeam Samurai mid-tower to demonstrate, and the straps were all nearly at their shortest length.  According to Sunbeam, you should be able to carry a case that is up to 21*8*22 inches.  That's just an inch short of handling a full tower monster like the In-Win Q500.