If you're still lucky enough to have a 1.25 GHz or 1.42 GHz model, you can run a modern OS that isn't Linux! Check out MorphOS, the single fastest OS for your PowerPC Mac.
Wow ...
This gives me the equivalent of a 25 year flash back in time, where there is such a wonderful world online ... things on the internet are positive and put you at awe, you find great information, new tools, new utilities, download this, download that, learn a new trick ...
Today I suddenly stumble on a compatible OS I never knew existed.
Long story short, I have a few older Macs around and always wanted to have my own miniature time capsule / computer museum, but in recent years found myself at odds with everything on the windows side and Mac side, because everything is so internet centric, nothing supports the right internet https or App Store security protocols any more, web pages now require GBs of RAM ... and honestly firing up a G3 G4 intel just became a headache with obsoleted browsers, authentication issues on the Apple App Store, etc. One learns of the browsers that are old Firefox or such forks, but even those are near extinction ... understandably, their creators are running out of steam while fighting a never ending tide of obsolescence.
So, thank you, MysticCow, for your comment and mention of morphos.
I may keep one of my G4 Cubes around a bit longer, if I can get that running ... G4 450? G4 500? 1.5 GB RAM?