OK... I'm not a conspiracy theorist by any stretch of the imagination, but I've had a chain of events that leave me wondering what's going on: First let me tell you my system: Dual G5 1.8GHz 3.5GB RAM. Last year I could download and watch 1080i HD quicktime videos ( trailers from Apple's site ) without problems, playing at full resolution with no noticable frame dropping. Then after a quicktime update ( don't remember which ), the performance fell down horribly to just a few frames a second for HD movies ( lower res videos still played fine ). The next quicktime bumped up the performance back to something reasonable where I could at least "kind of" watch an HD trailer, but still there were sluggish points on most videos. So last week I finally pony up for Leopard. Now I can watch 1080i trailers again without any problems and not a single frame drop that I notice. What the heck??? Is this because of Leopard supposedly offloading some of the work to the video card? I think I read that it does that right? I have actually noticed better performance all around with Leopard but most obvious is the graphics performance ( minimizing windows, dashboard, webpages etc ). I was mad at myself for not upgrading sooner!