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 of OS9.
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.