[dnanian]

An image created with the "Image" checkbox in "Options..." is actually a device-specific ASR image, and won't be portable to any hard drives other than one configured just like the original.

If you want to be able to use a DMG on the Mini, you should create it "directly" by saving to a DMG in the "destination" (2nd) pop-up. That should be portable.

Note, though, that you'll likely need 10.3.8 for your mini: I don't believe 10.3.7, as sent to a G5, is a late enough build (check the build # on the mini), even though the version "number" is the same. I believe 10.3.8 should work, though.