Mac OS X cannot be installed on this computer!

Hi there, I am having a problem that I seem to not be able to find the answer to, hopefully someone can help! I have a white macbook from Mid 2007 with Intel Core 2 duo. My hard drive recently failed on me and I was forced to buy a new one and install it. I put in a seagate momentus 250GB drive that the system easily recognized and formatted to Mac OS Extended Journaled with the GUID partition table. Once all said and done I pop in my retail copy of leopard 10.5 which I installed on all of my macs in the past with out and a problem and i get to the select language screen and then a window pops up saying "Mac OS X cannot be installed on this computer!" So I tried my original gray discs that have 10.4 on them and get the same exact problem. I have looked through many forums and everyone either said use the discs that came with the computer which i did or make sure the hard drive is formatted to GUID which I did as well. Someone please help!