Linux XP like 11.04, a remaster of Ubuntu 11.04. GnomeXP have been used as the default theme.

Download:

32-bit version:

http://sourceforge.net/projects/xplike/files/xplike1104.iso/download

md5sum for iso: cea085609043e78b1addc1e9ae2c611d

64-bit version:

http://sourceforge.net/projects/xplike/files/xplike1104amd64.iso/download

md5sum for iso: 61817bd7ffe147f262b458a47f0b4eae

If unity starts automatically during live session, you have to log out (i don't know how, but you can create a new user and switch user) and in again with "classic ubuntu" to get rid of unity and get the ordinary gnome.