WimpWall is the free Automatic Wallpaper Changer for those too wimpy to be bothered with complicated stuff.
Features
Runs automatically at startup, then terminates. Most other wallpaper changers hang around in your system tray, taking up valuable resources.
Chooses random image for wallpaper from folder(s) you nominate. Yes, you can specify multiple folders.
Recurses folders, to find more images. If you sort your images into folders, then this is a great time-saver.
Can automatically tile small images, whilst letting large images stretch or centre.
Displays jpeg (.jpg) and bitmap (.bmp) images
Gives opportunity to postpone wallpaper change, in case your desktop already has one you particularly like
Does not require Active Desktop
No program installation required
