Here’s a lovely addon for Windows 7, Bing Wallpapers that automatically update each week…
Windows 7 users need only to download the theme package from Microsoft’s offering page and double-click it to set up a “Bing Dynamic” theme. By default, the wallpapers rotate every minute or so, so you’ll want to head into the settings to slow things down a bit (click the “Desktop Background” link at bottom). You’ll get three months of Bing wallpapers through the feed, automatically updated each week.
via Gizmodo