So, I burnt an Ubuntu 6.06.1 LTS PowerPC iso to a cd (named "ubuntu-6.06.1-desktop-powerpc.iso" that I got from Ubuntu.com).
uh, if this is REALLY what you did, then you probably didn't get very far.
I'm new here, but I'm sure it has been discussed elsewhere on this forum that .ISO files are "images" of the CD that you're going to make.
Whatever software you are using to burn the CD, there will be an option for "Burning CD image" The ISO image is like a zip file. Within it is the meat you are after. The burning software when so told will "open" the image and place it on the CD so that it is ready to use, ready to boot if the image is of a bootable (like yours) CD.
Once correctly burned, the CD will no longer be named "blah-blah.iso"