While I was getting screws at the home depot, I took a look at their 'specialty screws and fasteners' and found some nylon spacers, that were just like a white tube. they were bout 1/2" long, and the same size hole thru it as the screws.
Screw goes thru the hole on the ipac, then the spacer, and then right into the inside of the cab. 1 on each corner and it is VERY secure, nicely standing 1/2" from the inside wood of the cabinet. Did the same in the back with the motherboard