Actually, if you have a G4 with 10.5, you can run Photoshop 1.0 on it....I keep an old laptop around just for that purpose so I can launch PS 1, 2, 3, 4, 5, 6, 7, CS, CS2, CS3, CS4 & CS5 on that machine...and CS5 & CS6 on my current laptop. I did a video of Photoshop 1.0.7 and Photoshop CS3 for Russell Brown to play at a Photoshop World in Japan (Russell didn't have the time to do it).