Yes...the G4 iMac's were an interesting design (first iMac's with a flat panel display). And $40 bucks was a pretty good price.
Are you pursuing getting this computer working purely for it's "eye candy" / "eye-appeal" for your art studio (photos & videos)...or do you actually want to use it for day to day computing?
As far as the frustration...it's really not that bad. Once you know what to look for...it's mostly easy. Back in post #4 I mentioned that you probably need/want OS 10.3 or 10.4 for the computer. No gray disks. You need the full install retail OS install disks (as you should have seen in that thread I linked).
The only frustration is finding a good price.
- Nick
p.s. Make sure you have enough ram for the OS version you choose.
p.p.s. Also remember that you are working with a 9-12 year-old computer. And finding things is not always easy or cheap.