I am moving some files from my old PC onto my mac and some of my .AVI videos aren't playing. It says that I need to download a plugin for it to play. It takes me to a webpage with some links. I downloaded the Divx codec and all it did was install a divx player. I am not sure if it installed any plugins for quicktime. I tried updating my QT software and it said I had the most current software. What am I doing wrong? Also, I am having trouble playing some mpg files too. Some are working whereas others are not. All of these files played just fine in my windows media player on my PC and no mac app seems to be working for me. I have a 3 week old MB. I have never experienced a problem like this before in all my years using computers.