Really Good Applications

VLC Media Player

Replaces Windows Media Player and Quicktime

Quit messing around with the above-mentioned applications. VLC will play everything, and it has more options. Very easy to use too! Find VLC Here
Did I mention it was open-source? Open-source means good, reliable, FREE software.

Firefox

Replaces Internet Explorer

You haven't heard of Firefox yet? Seriously, millions of people use it. 27% of all internet users use it. Why? Because it's extremely powerful, fast, and, uh, free... it's open-source. http://www.mozilla.com/firefox/

Open Office

Replaces Microsoft Office

Microsoft Office costs lots of money, and Open Office does nearly everything Microsoft Office does, and more! (Does Excel, Word, Powerpoint) Again, Open Office is open-source, which means good, reliable, and free. http://www.openoffice.org

GIMP

Replaces Adobe Photoshop

Photoshop costs a lot of money, and why pirate when you can use a free, reliable alternative? The GIMP is open-source, and is the best replacement for Photoshop. http://www.gimp.org