Here is the complete Ubuntu Theme pack which is Unity-like skin for Windows 7 or XP. Everything is covered: icons (Faenza for launcher and Humanity for the system), the Unity launcher, login screen, boot screen, Ubuntu fonts as well as the Ubuntu 11.04 Wallpapers.
Here is the Ubuntu Skin Pack DevianArt page even links to small utility that emulates the compiz cube (for more tools, visit the Maverick for Win 7 DevianArt page):
But of course, this is different OS, the skin has few issues. For instance, the windows controls are out of place in Windows 7, this being an old issue that occurs in all such skins.
Download Ubuntu Skin Pack:
For Windows 7 32bit || 64bit
For Windows XP
Note: the installer contains adware (browser toolbar) before installing make backup.