Installed without a hitch on my Dual G4 500 (512 mb ram). SMP support is dramatic, to say the least. I thought I'd just be playing with OS X, not actually usng it as my primary OS, but it's SO DAMN STABLE!! Classic is slow, and has 80% of the bugs I've experienced so far, but most apps run fine (mp3 players with drag and drop are lethal, though, hard crashes usually), even games run, but it seems the Classic --> OpenGL --> OS X --> OpenGL wrappers are inefficient, I lose about 20 fps or so in Unreal and Q3, other games, like The Sims, run fine, however. The big issue with Classic games is that you CANNOT tab out of them, or else the dock, as well as any finder windows, will draw OVER the game when the cursor goes down there. Not an issue if you pause the game and switch out as if it were OS 9, though. Aqua is goregous, not gonna go into it, you've probably seen screenshots. Hardware acceleration of windows/genie effect/resizes is really required, even on my Dual 500 G4 IE 5.5 resizes are dog-slow. God, I love this... never been so happy with an OS since 8 came out in '97...