Wallpaper Downloader is a freeware that allows you to download all Bing wallpaper images to your computer and change your desktop background with these images on a regular basis automatically. In the first-time run, it will download the past Bing wallpaper images. From then on, it will regularly check for new images and download them automatically.
Also, Wallpaper Downloader can change your computer desktop background with the downloaded images in slideshow mode.
What's new in this version:
Version 2.3 is a maintenance release.
Source : http://download.cnet.com