You may have thought, "what the hell is Ubuntu?" Ubuntu is a computer operating system based on Debian which is based on Linux. I won't go into details here on Debian or Linux but to say that Ubuntu is not Windows and vice-versa but a Ubuntu based computer can perform many Windows based computer functions. A Ubuntu based computer like Zorin even looks like Windows 7 to make you more comfortable!
If you want to write letters, email or shop on the web than Ubuntu can work for you. Ubuntu is free although like any Linux based operating system you can donate your time or money. Other fine free systems are Linux Mint and Zorin OS. You can install Ubuntu to replace what you have or install alongside Windows and choose at startup which one to use. It's not hard but there is a learning curve based on your patience.
You can download Ubuntu, Linux Mint, or Zorin OS from their respective websites. You can even try them without installing from the Live CD. Ubuntu Unity is the latest version which is 11.04. Websites like TOTAL OS TODAY can help you get started.