Wubi is an officially supported Ubuntu installer for Windows - Download Free

Wubi is an officially supported Ubuntu installer for Windows users that can bring you to the Linux world with a single click. Wubi allows you to install and uninstall Ubuntu as any other Windows application, in a simple and safe way. No need to burn a CD, just run the installer, enter a password for the new account, and click "Install". Wubi will download and prepare the required files, and ask you to reboot in order to complete the installation. You keep Windows as it is, Wubi only adds an extra option to boot into Ubuntu.
Wubi does not require you to modify the partitions of your PC, or to use a different bootloader, and does not install special drivers. Wubi keeps most of the files in one folder, and if you do not like it, you can simply uninstall it as any other application. Version 8.04.1 includes unspecified updates.