I have a 20inch iMac from 2008. The internal hard disk failed. I reinstalled OSX Leopard on a 40GB external IDE drive with enclosure. Everything worked fine.
I decided to purchase a 320GB SATA drive with enclosure with the idea of installing OSX Leopard on it, make sure everything is fine and eventually do the whole major surgery to replace the internal drive. I partitioned the 320GB drive with 2 partitions in GUID, 1 of 200GB and the other one of 98GB.
The problem I have is, I do the install on the GUID partition of the 320GB SATA drive (external), but the computer reboots and doesn't seem to find that bootable partition. It will just boot of the disc. One important thing to note though, at the end of the installation, it tells me to be ready with disc 2, but when it reboots, it NEVER asks me for the disc 2. It just reboots of the disc, so I am back to square one.
I did reassign the partition to be the startup disk, without success.

Thanks for your help