To play many different format media files, I see my friends using different media players like Winamp, Real (the worst), QuickTime (even worst, it bundled with iTunes) and others. These software puts some start-up programs which runs at start-up and stay in notification area forever. ITunes is needed if you own iPod, otherwise it’s a waste. If you actually see how many times you use those software and features, not much.
These programs sitting in memory, takes some processor time and it even phones back to home (collecting data).
There is one open-source software that plays *most* of the media files including DVDs. It’s MPlayer. You can get it from HERE or click on the picture below. I like the one program (that’s even only one 8 MB executable file) concept and it’s handles all.