Installing a fresh copy of leopard in another computer

So I recently bought a MBP and along with it I received 2 Leopard install cd's. Now I have a friend with a Mac Mini (intel core 2 duo) still running Tiger, I wanted to upgrade his computer to Leopard using these discs that came with my MBP, however when attempting to boot from these discs I receive this error "Mac OS X cannot be installed on this computer - This software cannot be installed on this computer"

So can I not do this with these disc's? is what I'm trying to do illegal?

any input would be appreciated.

Nope will not work as your disks are system restore disks which work with your model MacBook only. If he wants to upgrade is necessary to purchase a full retail install Leopard DVD which is black coloured, whereas yours no doubt are a silver grey.