Ubuntu is one of most active group behind modifying linux and making it easy for windows users to accept and try ubuntu linux with more user acceptability.
Out of the all those Ubuntu community has taken the initiative of proving desktop edition of ubuntu linux which can be easily installed and uninstalled from windows itself. The only thing that was quite difficult till now was to install ubuntu linux on a USB portable drive.
But now with uSbuntu Live Creator which is the safest and easiest way to install ubuntu linux on your USB portable drive which enables you to install and run ubuntu directly from your USB drive.
You can install ubuntu on USB drive either from a ubuntu iso image you have, or from a ubuntu installation cd and you don’t have them then you need download the iso image of ubuntu from here.