I have a first gen white macbook core duo. I am trying to install a new 320GB Seagate HDD in my laptop to replace the 60Gb drive. I installed it but I can't get the OS to recognize the Hard disk when it is installed in the computer. I have no problems when it is installed in an external case. I have booted off the Leopard disk but it does not show a drive available to format, I booted off the original drive in the external case and the disk utilities does not show another drive attached. If I put the 320GB drive in the external enclosure, disk utilities recognizes it right away. I have formatted it with GUID format but it doesn't work when installed directly in the macbook. Can anybody give me some suggestions. Thanks.