There is nothing Linux can do that windows can't do.
That isn't true. For starters you can find a version of any program that you want and download it for free. You can't do that in windows.
Other things that you can do only with Linux:
* Browse the web while the OS is being installed!
* Update your entire system, kernel, software, everything with just one click.
* Understand everything that goes on with my computer. Linux is open source, that means that I have access to all of the source files if I want them, and can get them easily. Windows is proprietary.
* Run thousands of pieces of software that run only on Linux. This is similar to what I said abouve.
* Easily install and run different graphical interfaces if I don't like the default setup. There are two main gui's Gnome and KDE, and others too, you are stuck with the same old windows look.
*Install the same copy of my OS on multiple computers without worrying about license restrictions or activation keys.
* Run my computer without needing to defragment my hard drive, ever.
* Run multiple desktops simultaneously, or even allow multiple users to log in and use the computer simultaneously.
That is just a small portion of the long and extensive list of things that you can do on Linux that you can't do on Windows.