One of the greatest features of the computer and internet is that of freedom of choice: you can choose your operating system, your hardware, software, and have access to far more information and media that anyone has ever before had.Unfortunately, software has largely become dominated by a handful of different programs: Microsoft now has a voluntary monopoly over most operating systems and the software that they run. I won't go into the details, but a system with no competition does not foster creativity, innovation, or accountability. Choose software based on its merits and principles, not popularity.
The following are alternatives to the most commonly used operating systems and software that I personally use and would recommend.
Right off the bat, lets start with the big one: your operating system. Chances are, you use Windows. I can just about guarantee that you aren't a supporter of the Microsoft Monopoly. A voluntary monopoly is one thing when the software actually works but entirely another when it's crashware. Sure you can but a Mac, if you have the money and don't mind the labels that are sure to be affixed to you, but it's still proprietary. Fortunately, some very smart people have spent a lot of time creating alternatives.
Linux is really the way to go, but there are so many different distros that it can be hard to choose: I would recommend Ubuntu, although Mint is also an excellent alternative, and both work well for newbies, although I would recommend Ubuntu overall, but that's something to be saved for another post.
Windows media player has a whole host of alternatives. I personally use two: Songbird to manage my music collection, and VLC for video playback, along with quickly opening any other media files.
Although it's been said over and over, it still bears repeating: OpenOffice is a free alternative to Microsoft Office, and is every inch it's equal in the standard office suite tasks.
FireFox is the king of open-source, and for good reason. A lot of people spend time in their browsers, and the ability to customize and create to your hearts content is quite simply a necessity.