Wubi is an unofficial Ubuntu installer for Windows users that will bring you into the Linux world with a single click. Wubi allows you to install and uninstall Ubuntu as any other application. If you heard about Linux and Ubuntu, if you wanted to try them but you were afraid, this is for you.
Wubi claims there is no partition modifications or bootloader changes to Windows and that is easily uninstallable. While I haven’t tried it yet (perhaps because it will require me to install Windows) , Tom Merrit (the linux hippy) was tweeting about Wubi last week. If you have used it, please let me know in the comments what you think of it!