Final Cut Studio 3 will work on a G5. Its installed on my Quad G5 and runs great (Final Cut Pro anyways). Its actually all Universal applications, but the official installer doesn't let you install on a PPC by default. I've never actually tried in on a G4 since I don't own one with a GPU that would support the software. I know my 128MB 9600 Pro in my dual 2.0 G5 wasn't enough to let it startup. Final Cut Studio 2 is actually given G4 support right from Apple.