The discs that ship with a Mac are always CPU and model specific - so the discset that shipped with a certain generation and certain build of a certain Mac Mini will only work on the Mac Minis of the same generation and that were shipped with the same build. Thus, no, they will not work for a G4. You will need to get a different set (a retail set - everything else is the same way, cpu specific) to use on your Mac Mini - or just decide that you are happy with whatever OS and build you have on it at the moment.