I'm on a 1.8 GHz PowerPC g5. I had been running 10.3.5 (or whatever the free upgrades from there would have been) until recently when I upgraded to 10.5.6. in hopes of speeding up web browsing. It didn't work (the problem I think is how I surf...opening lots of windows at once). In addition, now my peripherals only show up on the desktop (not in the finder) and some of my older software is acting funny. I have Quark 6 and Adobe CS2, which I'm reading will work but have issues, and I don't want to upgrade. Can I just use the original disk that came with the computer to revert back to 10.3? I don't want to do a clean install and I'm concerned about losing data...I have my time machine backups--and I know my computer won't automatically backup anymore (maybe there's inexpensive software that will do the same thing for me?). I also have disks for 10.4.8 that came with my laptop, but I'm reading about issues with Illustrator and it's just not worth it for me.