a Problem while Installing MAC os x 10.5.5 On a Brand new Macbook 13'

Hi,
i recently purchased a brand new mac book.
i have deleted the snow leopard and insert a mac os x 10.5.5 Installation CD

while it booted it asked me for my language and when the installation statred up it said mac os x cant be installed on this computer.

so i took the original mac book cd's and run the other installation of 10.6 and it run ok..

why doesn't it let me run 10.5.5 ?

I Really need help!! Thanx!!!!

1. If you're using the discs from another machine, they are machine specific and will not install.

2. If you're using a retail disc, it probably does not have the drivers required for a new machine.

yes im using a 15 intch macbook pro cd...

ohh.. i Understnad now.. i need a 13 inch..

i see ..thanx!!! a bunch!!!

Has nothing to do with 13" vs 15". The discs that come with a Mac are machine (or system specific). You will not be able to use the discs from one machine on another unless it is the same system (basically identical hardware).