Windows XP A to Z -
Change Orginal Desktop Wallpaper
Super Admin
By Super Admin
Published on 02/23/2005
This is more of a fun tweak than it is useful.

Change Orginal Desktop Wallpaper

Go to run, type regedit press ok.
when that comes up go to HKEY_CURRENT_USER>Control Panel>Desktop
Now find the orginalwallpaper, right click and select modify.
In the text box type the path to the file you want to be your orginal desktop wallpaper.

There ya go!