How can I run Ubuntu from Windows XP operating system?

How can I run Ubuntu from windows XP operating system?
Ubuntu is one of the most popular operating system of Linux but most of the people are afraid about the Linux System. But Linux can be popular when people are favorable with it and I think Ubuntu is the easiest operating system of Linux.
If there is any system to run Ubuntu by Windows XP the general people (basically the third word people) can use Ubuntu as their operating system. So please explain whether it is possible or not. If possible what is the process?
