I'm selling a MacBook that currently has 10.4 on it. I recently bought a new MacBook. When I tried to install 10.5 (with the install discs that came with the new MacBook) on my old MacBook, it wouldn't let me. What if I partition the hard drive on the old MacBook (and wiping out the hard drive), and then installing 10.5? Would this work with the install discs that came with a different MacBook? Or is there a security measure that prevents this, as well. Thanks!