A Windows based installer for Ubuntu Linux is now available:

We have a development version of a Windows based installer for Ubuntu which is designed to be:
very simple to use
provide a no-risk installation
no repartitioning the hard disk
no changing the windows boot loader
Easy uninstallation.
Low risk
Doesn't use a virtual machine
Doesn't significantly reduce performance of the resulting installation
Resulting installation supports everything a normal install does.
Fast install

Full announcement:
LinuxCompatible