I just finished adding some hardware to my Quicksilver Powermac.
I purchased a surplus APS external SCSI drive housing from a vendor on Ebay.
Originally it housed an 18GB drive which I've replace with a 75GB 15K RPM Ultra320 drive using an 80 pin drive adapter.
The drive connects to the original power and controller cables of the housing and I have the whole thing connected to an SCSI controller in my Mac.
Now when I have the drive powered, the system can boot OSX (quite fast).
And when its not powered, the system boots MorphOS from the internal ATA100 drive.

I couldn't resist updating this setup when the chance came to get a good buy on an eSATA controller card.
I just won a Sonnet Tempo X4p PCI-X SATA II RAID card on Ebay ($25 plus $15 S&H).
It will work in my G4's PCI slot and can be moved to a G5 later.
I also picked up a Rocketfish RF- HD3035 SATA Hard Drive Enclosure so that I can install one of my SATA II hard disks into it.

Now I just have to figure out what to do with the SCSI hardware (I think I'll use it in my PC to backup my hard drive).

Edit - What to do with the SCSI drive? Keep it. The TempoX4p does not support bootable drives! My mistake. I guess I'll save it for use in a G5.

[ Edited by Jim 29.03.2012 - 17:49 ]