In Windows 7, Microsoft has included a new desktop customization feature called Aero Themes which enables users to customize the desktop wallpaper with a matching glass color, screensaver, icons and sound scheme of their choice.
Here is a collection of different Windows 7 themes including the ones from the finalRTM Build of Windows 7.
Themes from Windows 7 (RTM Build 7600.16385)
The “Ultimate” Windows 7 Theme Pack
Michael Jackson Themes for Windows 7
Windows 7 Box Art Themes for Ultimate, Professional and Home Premium editions
Mac OS X Snow Leopard v10.6 Themes for Windows 7
Installation Instructions: Double click the downloaded .themepack file to install it. These themes will only work on Windows 7.
Download Windows 7 Themes Pack (RTM Build 7600.16385)