Is your G4 a Stock Powermac G4 Ethernet? If so it's probably a 16Meg ATI AGP card. I am pretty sure mine went up to 1280x1024 but since I upgraded it to a Radeon I can't remember anymore. Where are you trying to change the resolution? Not at the little monitor by the clock I hope. Open Display from the System Preferences and click on the Display tab. All the resolutions your card supports will be listed there. If 1024 is the highest then it's probably a limit of the built in graphics card. You can get a better card if you need to.