I hope to soon receive (like this week) a new C2D MacBook Pro. I will also be getting a 160 Gb firewire HD. I have an older PPC G4 that will continue to be an inuse machine. What I want to co is to create a bootable paritition for each machine on the external as an emergency recovery device. I understand that the two machines cannot be booted from the same system image (at least not with OSX 10.4.8). Indeed creating the two bootable images require just a bit of magic which I think I have sorted out. My question is how to partition the disk. Several configurations come to mind. One would be to create two equal partitions, one for each OS image. Another would be to create one parition of about 10 Gb and leave the remainder of the disk in the other. Then install one image in the smaller partition and the other in the larger. Yet another possibility would be to create two small (say 10 Gb each) partions one for each of the OS images and leave the remainder of the HD as a scratch area and storage of backup files. Finally throw in to mix that I will be using the external HD to provide a large scratch area for Photoshop. How would you partion the drive and why?