I heartily recommend Mac OS X 10.5 Leopard for your G5, though a lot of my readers get a ton of use out of Debian Linux or some other variant. That’s great. But there is one more option off the beaten path – MorphOS.
MorphOS is not an open source operating system. In fact, I initially thought it had some connections to AEROS, which is an attempt to use Linux underpinings to recreate the Amiga OS, but I was wrong. Amiga OS was never super popular, but it had its uses and was great for media editing workstations. In fact, that was my first experience working with any version of Amigo OS, way back in high school in a video production class.
I can’t say I have a love for Amiga OS or enough experience as to extoll its virtues, but MorphOS has emerged in recent years as a viable alternate for PowerPC machines. Again, it’s not open source, and you do have to pay for it. But you get a slick, capable enough operating system that continues to evolve and runs super fast on older machines, especially our Power Mac G5s (with some caveats).
Check out the video below, which mirrors my experience of giving MorphOS a test run on my Mac Mini G4. It boots and loads quick and is pretty damn responsive.
MorphOS continues to add support for PPC machines. Check to see if your G5 (or other older Mac) is compatible. It appears you can only use certain Mac models, but you also need a Radeon video card (meaning my G5 won’t run MorphOS). The base system comes with a small package of apps to get you started, including a decently updated Webkit browser. The GUI leaves something to be desired – I would like it to be a bit more clean, but it might work for you. I gave it a good run through on my Mini, and I really enjoyed the responsive and appearance of stability. Maybe when TenFourFox dies out, could this OS be an another option to keep these old Macs purring?
If you want to try it out, you can download a CD image and run a 30 minute demo. I’d recommend it if you want to burn an afternoon. You will have to pay around $79 Euros to get your own copy, but updates are free after that.