What's the latest operating system I can use on my ibook G4?

[jway123]

Is it Leopard 10.5.6? I know I can't use Snow Leopard. Is it worth it? Where can I get it least expensively, it's not in stores.

 

[Eidorian]

The last retail disc would be 10.5.6. You'd update to 10.5.8.

 

[Gregg2]

Search for it online

Some say you can get it on eBay for about $80

 

[JediMeister]

Yep, 10.5.6 would be the the most up-to-date revision of the 10.5 retail disc you could acquire. Some university bookstores and Mac-compatible software resellers may offer it at a discount since they're trying to clear stock, it's probably also on eBay (what isn't these days?), and if you want, I'm sure an AppleCare agent will be open to selling it to you if you don't mind the probable delays in the shipping process since it's more than likely no longer being actively printed.