Download Windows 7 Themes, Desktop Backgrounds and Gadgets Officially
Go to the link mentioned below and download a variety of stuff for Windows 7.
Windows 7 Themes
To download a theme, click the Download button there, and then click Open. The theme is applied to your desktop and added to Personalization in Control Panel.
Windows 7 Desktop Backgrounds
Click the Download button to open a desktop background, right-click the image, and then click Set as Background.
Windows 7 Gadgets
Windows contains mini-programs called gadgets, which offer information at a glance and provide easy access to frequently used tools. For example, you can use gadgets to display a picture slide show or view continuously updated headlines from your favorite resource. You can customize desktop gadgets by changing their settings, resizing them, keeping them on top of other windows, moving them anywhere on the desktop, and making other changes.