Is it possible to have OS 10.5.x on my MBP 15"?
Yes. You need to purchase and install it.
Will any 10.5 instal discs work or is there a specific set?
Retail installation disks only. Those which originally shipped with a Mac won't install.
How do I tell the difference?
Black disks are retail ones. Gray disks shipped with a Mac.
Thanks for the info.
Retrieving data ...