Get a changing desktop background without additional software

                  You want more variety on your desktop and thus want the wallpaper to keep changing every few minutes. Till now, you have been using a third-party tool, but Windows 7 can do this on its own.
                  Right click a free place on the desktop and select the context command ‘Personalize’. Click the
‘Desktop background’ link in the next dialog box. You can now select an image by clicking any one of the
thumbnails. Then simply click the next image for your future slideshow. As soon as you hover the cursor over
the image, an empty checkbox is displayed in the upper left corner.
                  Here, click to add a check mark for adding an image to the slideshow. You can repeat the process to add some more  images.  It  will  also  go  faster  if  you keep the [Ctrl] key pressed and then click the desired images one after the other or simply click ‘Select All’.
                 If  you  select  more  than  one  image, Windows activates the controls under the heading ‘Change image every…’. In this combination fi eld, select a time period between ‘10 seconds’ and ‘1 day’ after which the background image should change automatically. Enable the ‘Shuffle’ option if you want Windows to use images in a random sequence. In the ‘Image position’ combination field, define the display method of the wallpapers on the desktop. For example, Windows can increase the size of the image till it fills the entire desktop, maintaining the aspect ratio. Depending on the image format, the image is cropped from the upper to the lower edge. The ‘Stretch’ option is not very practical because Windows then stretches the image to the
desktop dimensions