1) Navigate to:
HKEY USERS\ .DEFAULT\Control Panel\Desktop
2) Double click the wallpaper value, and type in the full path of your image and the filename.
3) To tile the image set "TileWallPaper" to 1
4) To Stretch the wallpaper set "WallPaperStyle" to 2
5) Close the registry editor and the changes will take place when you Log off.
This could be your favourite image or picture as long as it is a .bmp or .jpg
IMPORTANT: This procedure contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article numbers to view the Microsoft Knowledge Base articles