I just replaced a dying HD with a Toshiba (MK2018GAS) 20gig HD.
I have read about Brass shim on the HD. But, the magnetic Switch still does not work properly. I can wakeup PB with a magnet. Otherwise install of OS 9 and Jag went great on the new HD after making 2 partition, one for the system 7.75gig and the second 12.25 for storage. Both systems are installed in the "System" partition.