1. My eMac is aging as new updates and upgrades keep coming, so my OS 10.3.9 is not new anymore - and so I am searching for granting it new life with as modern as possible Operating System, one which will work on my 1.25 GHz PowerPC G4 512 MB DDR SDRAM machine with DVD (Super Drive CD/DVD) 2. I am also wondering if a system made for my wife's macBOOK 10.5.2 will install - and if it will be as new install or work like a system upgrade, so I do not loose my documents and many applications and all the stored and memorized links in these applications. Please note I love it because it runs my OS-9 applications which are still good for website publishing and photo-editing and so on as I have all systems and 27 Macs - including a yet new 128k Mac...lol 3. Will I need to back-up all my machine on external drive to be safe.