VLC Media Player
Allright, anyone who has ever downloaded movies off P2P will know this. You sometimes just get unplayable, third-world formats. Why? Because people just don't get it, which is something we can't fix. However as far as the movies go, there is hope in the form of VLC Media Player. VLC is the solution for anyone who has had issues with playing movie formats. It's available for a slew of platforms from Windows to Linux to PocketPC. I even swear by it. If VLC can't play it, it's an unplayable format. If you download movies off the web, P2P, or wherever and go to open them in Quicktime, you may find yourself with an error message about the codec. Just use VLC. It can handle VCDs, AVI, MPG, DiVX, xVID, and many other acronyms. Another great feature is that it can do movies full screen and has great control. If you don't have Quicktime Pro, you're kinda out of luck here which is why VLC is so great. Plus, it's free, so go get it and try it out now if you haven't already.