I have a Macbook (Model A1181, Core Duo)
The hard drive failed.
I had another hard drive that I pull from an HP laptop that worked fine.
I blew away all the partitions and did not format it, and put it in the Macbook.
I put in the Snow Leopard DVD and turn the machine on;
I hold dow the "Option" key.
The image for the DVD shows up but not the image showing that there is a hard drive present.
I click install; the Apple symbol shows and the little icon just spins. I let it run for a couple of hours and it never changed or went further.