I bought a 15" MBP recently, and wanted to upgrade my wife's 13" MB to SL using the install disc that came with my machine (Disc Version 1.0, 2Z691-6530-A.) Whenever I try to upgrade her OS, I get an error saying the "OS 10.6 cannot be installed on this computer." Her machine is a 2GHz Core Duo with 2 gb of RAM and a 150 gig hard drive, so no technical limitations. Is it a check that Apple puts on the install disc that ships with a new machine? If so, anyway way to bypass?