My friend has a PowerBook G4 (Al 15" 1ghz) that is having some problems. It seems to be the hard drive, so I offered to try a replacement with a hd from an old PC laptop I have. The transplant seemed to be a success, but the hard drive is not being picked up in target disk mode or in Disk Utility from a install disc boot up. Could this be because I forgot to format the hard drive before removing it from the PC? I would think the drive would still be seen. The drive was working in the PC. It feels like the drive might not be spinning up at all in the powerbook, but I feel that the install went well and that the hard drive cable was replaced correctly. Is there anything I could have missed?