Ubuntu on Windows: Wubi

“One of the signs of Ubuntu’s soaring popularity is that the
computer press enthusiastically credits the distribution with
anything that happens to be new in its release. A case in point is
Wubi, an application for installing Ubuntu in Windows as a
loopmounted device. The truth is, while Wubi installs a copy of
Ubuntu whose performance is first-rate, the assumptions it makes
about users’ knowledge probably work against its goal of
encouraging Windows users to try Ubuntu.

“Contrary to the impression you might get from media coverage,
Wubi is nothing new. GNU/Linux distributions have been co-existing
on Windows file systems at least since Monkey Linux in 1997, and
other distributions, such as Damn Small Linux, have the same
capacity today…”