Jim,
if you put 8000 in for X step per unit and then you MDI a move of 1 inch and it only moves 1/2 inch then that means you need 16,000 in the steps per box. I was assuming one or two factors when I worked out the X value, firstly that your steppers are 200 steps per rev and secondly that your drives were half stepping. Your motors may be 400 steps per rev (not so common) or your drive may be 1/4 stepping, they could even be 1/8 stepping or for that matter even more.
Hood