Deigh, you're going to need to be a lot more specific about the model of "G4" you've bought. This "the Mac just works" expectation (heh!) that some people have comes at a cost. Extremely limited compatibility lists and brutal
end-of-life policies - and you're talking about a transitional period where OS9 was being phased out and OS-X was being introduced. Only SOME models were allowed compatibility with OS9 during it's sunset years, and even then it was usually a specific version
Have a good look on your machine and see if you can find a nameplate... Then have a look through this OS9 compatibility page
and see if you can find your model.
Assuming you have a"PowerMac" not an iMac G4... PowerMac G4: How to differentiate between models (part 1
and part 2
Otherwise, start with Apple's suggestions on How to find your Mac's model and age
... and google is your friend also.
"dsakey" on trademe. Apple II's are my thing.