Debian Unstable (often called Sid) is a branch of the Debian operating system designed for active development of new versions of packages. It is considered the most recent, but also the most unstable of the three main branches of Debian. Other software comes with Oldversion and runs under Wine. Xfce Desktop Environments
I do find recreating the whole theme of XP pretty impressive, it must have taken a lot more than just a “skin import”.