I have a couple of different Macs around my house. I recently wiped and did a clean install on my MBP with the Grey Disks (10.4) that came with the MBP. I also have an iMac that shipped with Grey-Disk 10.5 OS. I wanted to upgrade my MBP to 10.5 and tried to use the iMac's Grey Disks but got an error message stating that "This software cannot be installed on this computer." Are the disks that ship with certain model of computer specific to that computer? If not, why can't I use the 10.5 disks that shipped with my iMac on my MBP (that shipped with 10.4)? Are there any workarounds? Thanks, J. P.S. There's a program I have that works on 10.5 that doesn't work on 10.4 and changed on 10.6 (so I want to install 10.5 specifically).