[Osiris]

Many novice users fear the technical process that has do be done before or during the installation of a Linux distribution. Partitioning is something that most are not familiar with and the fear to do something wrong and wreck their standard operating system is probably one of the main reasons why many users do not install a Linux distribution.
Wubi is a sweet little program that lets us install Ubuntu - or Kubuntu, Xubuntu and UbuntuStudio - without partitioning your hard disks at all. “Wubi adds an entry to the Windows boot menu which allows you to run Linux. Ubuntu is installed within a file in the windows file system (c:\wubi\disks\system.virtual.disk), this file is seen by Linux as a real hard disk.”
So, the main difference is that Ubuntu is installed into a file instead of its own partition which is a great way to test the Linux distribution without having to partition your hard drives. Ubuntu is not running in a virtual environment at all, this is a real installation. The Windows boot manager will give you the choice to either boot Windows or Ubuntu at every startup from then on.
It is also easy to uninstall Ubuntu again by simply using the Add or Remove Programs dialog in Windows.

I can’t think of an easier way to try and test Ubuntu on your computer without installing it. Live CDs are nice but I personally do not like to play disk jockey whenever I want to try the Live CD.
Wubi is workinx extremely stable although it is currently in beta.