Okay...there's no reason to regret getting your Mac just yet. It takes a bit of getting used to, but once you figure some things out, it's a breeze to run.
Your Quicktime version should be kept up-to-date through Software Update...you shouldn't have to manually go download new versions of it. So it sounds like maybe the first thing you should do is go to Software Update (in the "Apple menu" in the upper left corner of your screen) and run that to see what software updates are available for you, and then install them. Depending on what's available, you'll probably have to restart your computer after installing the updates.
Crap...fire alarm just went off in my building. I'll be back...more later...