Here are my main reasons why Linux is better than Windows (numbered for clarity, not order):
As-is, without needing any downloads/updates, features of the operating system (by default):
1. Free/Illegal to make "unfree"/ISO image available online (legal)/Encouraged to make copies and distribute/redistribute.
2. Drag-and-drop to reposition the placeholders for open windows on the taskbar.
3. Contains virtual desktops.
4. Get two CDs of the operating system shipped to you at absolutely no cost by providing a name and address.
5. Huge amount of dedicated (and "official") community forums/support.
6. Contains an office suite.
7. Multiple languages selectable at boot time.
8. Low minimum system requirements.
9. Contains package management software.
10. Single CD install
11. Can be tested (fully functional) without installing
12. Can hot-plug PS/2 keyboards and mice
13. Contains Perl (Practical Extraction and Report Language)
--Ubuntu (one of the latest-and-greatest of Linux) had all of these features by December 2007
--Windows Vista Ultimate (the latest-and-greatest of Windows) had none of these features by December 2007
Make your switch today!