My wife has an iBook G4, 1.33 ghz PowerPC CPU, 1.25 GB Ram, 55.7 GB HD operating on OS X 10.3.9. We usually use her computer to watch online video. As some of the video content requires OS X 10.4 or higher to play, I was wondering if a software upgrade would be worth the money. (Before you say buy a new computer, my wife really doesn't want to spend money on a new computer) So if an upgrade makes sense, should I upgrade to Tiger or Leopard and where is the best place to shop for OS X installation dvds? I was looking on Ebay but I'm worried that a used install disc won't work.