A user-friendly port of Linux that runs like a standard Windows app and uses the FAT filesystem. Users sacrifice speed and functionality, basically, for ease of use and for not having to commit themselves even in a small way by making a new partition. If people just like the look of KDE, which it uses, they may be better off running KDE-cygwin. It could be a good way to try Linux, though no one would use it as their main desktop OS.