Now, let's see how we can make Bing Desktop wallpapers (regular update) as your desktop slide show source.
1. As first step to achieve this you must install Bing desktop application from http://www.bing.com/explore/desktop
2. After installing launch your Bing desktop application and go to wallpaper tab as shown below.
3. Now click on the check box (make the bing homepage image your desktop background) and click on the image you want to keep as your desktop background.
4. Now you should be able to see this image as your desktop wallpaper.
5. Hold on, this won't be shown as slide show only the image you have chosen here will be shown.
6. Now lets make this slide show (open your desktop background from Control Panel\All Control Panel Items\Personalization\Desktop Background).
7. Your desktop background screen might show the following folder "C:\Users\<User name>\AppData\Local\Microsoft\BingDesktop\themes". Now choose all the images in the list.
8. Now you should be able to see the shuffle and time options on the bottom of the desktop screen getting enabled.
9. Choose the time interval you want and click on save changes.
