My daughter handed me down her Ibook G4 (late 2004) that came with 10.3 operating system. Believe it or not, this is a step up for me! I'd like to clear it all out, and start clean. Of course, she can't find her install disk. I'm thinking about installing 10.4. I have a 1.2G HD and 512M memory. I also see full installs and upgrades. What do I need? Does a person have to reformat it before installing either? Will either the full install or upgrade automatically clear out the old? There isn't a program already stored in the laptop that will reformat it, is there? Go easy on me, I'm not real savvy with all this.