Spent some time tinkering with some old PowerBooks recently:

• I now have 3 non-working PowerBook 100‘s. All seem to have failed in the same manner (motherboard issues I think). The good news is they are really easy to take apart. The bad news is they use 2.5″ SCSI hard drives… I should be able to sort the motherboard issue out (hopefully).
• I now have a working PowerBook 54oc. I repaired it using parts from a busted PowerBook 520c. It has a 320MB 2.5″ SCSI hard drive and 12MB of RAM. I have installed Mac OS 7.6 on it (will upgrade to 7.6.1 as soon as I can). It is a very nice laptop – especially the active matrix screen. I really like the PowerBook 540c, on-board ethernet and modem (mine has an internal modem installed). Having SCSI, ADB and a serial port is cool also.

I think the biggest problem facing people who collect old Macs (in particular PowerBooks) is the internal 2.5″ SCSI disk issue. These invariably fail and are getting harder and harder to find. Ideally, a SCSI to IDE converter should be made (or even a SCSI to CF adapter) but I don’t think this is going to happen. At least with desktop Macs the 3.5″ SCSI drives can be replaced by more modern SCSI drives (with the appropriate adapters).