I just purchased an air last week, so pardon the question. My mac says I can upgrade my OS to 10.5.7 with a size of 737MB to install along with itunes and a Quicktime update. The update (and programs) download fine, the problem comes in with the install. When I shut down my computer and begin the install process, the status bar moves only a little bit, then stays put. I left my computer on my desk for about 30 minutes and it is still at the same spot. I had to restart my computer by holding the power button. I have tried to install these programs/updates a few times, and always have the same issues. My questions is, is this normal? Should I leave it on overnight to install the update? By the way, this board is great. The info here has been very helpful!