If he installed the OS while the drive was attached to his machine, and you moved the drive to YOUR machine, that could cause problems.
Different motherboard drivers
Different BIOS settings (SATA drives can run in 2 modes, AHCI (better) or IDE (compatible with older systems). There should be a method in your BIOS to change this.
What you should do is install the OS from your computer, not try to run the version installed on his.