Ubuntu is a Free computer Operating System (OS) based on Linux, built by a worldwide team of expert developers. It contains all the applications you need: a web browser, office suite, media apps, instant messaging and much more. Ubuntu is an open-source alternative to Windows and Mac.

You can do anything in Ubuntu that you can do with Mac & Windows, you just have different tools.

They have IE & Safari, we have Firefox.
They have Photoshop, we have Gimp.
They have MS Office, we have Open Office.
They have several different Chat/IM applications, we have Empathy for them all.
Not only does Ubuntu have an application similar to the other guys, but Ubuntu's applications can open files created by their applications.

If you're looking for the perfect desktop, customized just the way you like it - from where or IF you want the gnome panel task bar, to what color fire your windows burn up in when you close them. Yes, you read that right. Thanks to compiz, Ubunutu's composit manager, your desktop will do things you never imagined, like wobbly windows, desktop cube, & exploding windows!

Are you tired of viruses? Nothing is 100% but the odds are in your favor with Ubuntu.