I have a G4 DA which originally had dual 533 MHz processors. It's maxed out with 1.5 GB of RAM, but the thing that made the biggest difference for me was a new video card. I'm running a flashed GeForce 6200 card, a solution that seems to be quite common for G4's, and I can get a steady stream. I eventually upgraded to a single 1.5 GHz processor, but that made no difference at all. There is some difference between Youtube videos. I've made use of some for physics classes, and have a buffering problem with some on 2.4 GHz P4 machines running XP. Other videos play flawlessly. Smaller works, but flash on anything other than an Intel dual core is problematic; it's just too CPU intensive. IMHO, it would help if flash would make use of our G4's vector processors, but don't hold your breath. Adobe is not real happy with Apple these days.