Using a Flickr stream as a Windows 7 background slideshow?

Is there an app that will let me choose a Flickr photostream to be used as background slide show in Windows 7?

You can use John's Background Switcher

John’s Background Switcher (or JBS for short) periodically changes the background image on your computer (like every hour or every day) to something interesting. You can specify which pictures to choose from:

• Individual pictures on your computer.

• Folders containing pictures on your computer such as ‘My Pictures’.-

• Flickr photo sharing – selecting pictures by person, tags, sets or
  just plain random. You never know
  what you’re going to get next!-

• Facebook – your friends photos on your desktop!

• Vladstudio wallpapers – choose from the coolest wallpapers on the net!

• Any Media RSS feed – choose pictures from sites like DeviantArt, Photobucket, LOLCats and Zooomr amongst many others!

• Phanfare web albums – keep up to date with your friends and family.

• smugmug photo galleries – yours, your friends, anybody’s!

• Picasa Web Albums – choose from specific albums or any search text.

• Webshots – if you’re a Webshots user, you can choose from your online or downloaded photos and collections.

• Google Image Search – get pictures from anywhere across the internet.

• Bing Image Search – not a Google fanboy? Then Bing is for you!

• Yahoo! image search – the internet is your oyster!

There is a Bing Wallpaper Theme that uses an RSS feed to pull down images. You can try replacing the RSS feed with the feed for the photostream and see if that works.