No less than 3" of protection from the case itself to the box. If you have access to the foam that you can use to mold around the computer that would be the best option. UPS should have something you can use to do that.
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MacBook 2GHz Intel Core 2 Duo w/ 2GB DDR2 RAM & 120GB SATA 5400RPM HDD
Canon Rebel XTI
Google Cr-48 Beta Laptop