Luna silver is a nice theme which was found in windows xp but Satukoro had created the same them for Windows 7 users,see the screenshot below:-
It will give you Windows Xp look and feel in your Windows 7.
Installation is Very simple just extract files using Winrar Or 7 Zip copy theme file and folder and paste it in %Windir%ResourcesThemes folder and then apply it through Personalize window
You can download this theme by using following link:-
P.S. You will need Universal Patcher to use 3rd party theme in Windows 7.Universal can be found in Recommended Section.