This one is directly bootable in a VM as a mounted ISO, which is probably more convenient. Other images available seem to have been dumped in a way that made them not directly bootable, requiring you to burn it to a physical disc first. I have also included a bootable image of the installation media, should you want to install your own clean virtual machine and/or physical hardware. Here's a clean installation of Mac OS X 10.4 Tiger PPC, fully updated and ready to be used with qemu.