I have an older G4 eMac with 512Mb RAM. I upgraded the CD-Rom to a DVD burner and am installing Feisty on it. I did however run into issues just getting to the install. Here are the steps I followed to get a successful install started from the Live CD.
1. Download the ISO from here. (I grabbed the one labeled "Mac (PowerPC) and IBM-PPC (POWER5) desktop CD ").