[dnanian]

Hey, Brad -- good to see you here!

Your story wouldn't be fantasy if you were on an Intel Mac: Intel Macs can boot from GUID, and so you'd be able to format and store a partition on it that both machines could recognize.

But, PPC Macs can't really do that. While they can recognize and back up to GUID volumes, you can't boot from them.

If the bootability isn't a big deal (to me, it is, since it means I can test my backups and get up much faster), then you can partition as GUID, format the PC one with NTFS (which can't be written to by the Mac, but that shouldn't be a problem), the Mac side with HFS+, and be all set.

You can't really use the same partition, because there's no "high-function" format that works with both. You could purchase additional software to have Windows be able to read/write HFS+, but it's not an inexpensive outlay, and I'm not sure I would trust it with a backup.

Of course, there's another option. You could keep the drive attached to the Mac, format as HFS+, and share it with the PC using SMB/Windows Sharing. The Windows drive would see it as compatible, and the Mac could write directly. No boot for either, of course.

(Remember -- you can boot from a full image backup once restored, just not directly.)

Hopefully that gets us part way to understanding... let me know if you need additional follow-ups.