Your iMac G4 is limited to OS X 10.4.11.
The processor is too slow for a native install of 10.5 - but you can still get the "helper" utilities that can give you a work-around to install 10.5
1 GB of RAM is the maximum for your iMac G4.
What OS X version is printed on the label of disk #1?
If the set of "power mac g4 restore disks" are grey disks, then they will mostly be useless to you, although you COULD boot to the disk #1, and run Disk Utility to format the hard drive - but not much else. It will only install on the Mac model that it originally came with.
You'll need a commercial OS X install to get an OS X system installed. Those disks will be black. The best for your iMac will be Tiger (MacOS X 10.4.x)