Change the visuals and sounds on your computer:-

 

 

The Personalization screen shown above which can be accessed via Control Panel, Personalization is where you can change any aspect of your Windows appearance such as Desktop Background, Colour Scheme, Screen Saver and Sound Effects

 

Each item can be changed individually using the icons at the bottom of the screen, or you can choose a predetermined Theme in the top window

 

A new feature of Windows 7 is that some of the themes contain multiple background images which change automatically every 30 minutes - this can be customized to a period of your choice by clicking on the Desktop Background icon at the bottom of the screen, and changing the duration in the "Change picture every:" drop down list