So I've been using Windows DreamScenes for a little bit now and decided to give DeskScapes a try.

Here's a good background information site: http://www.istartedsomething.com/20070108/windows-dreamscene/

Here are the key differences:

Windows DreamScene at a glance:

Windows DreamScene is an animated wallpaper technology that plays high-definition video content as your wallpaper. The key ability of it is that it can do so without using significant amounts of CPU (basically the decoding of the video is the only real CPU use involved).  The animation itself is run through the hardware accelerated DWM.

• A Windows Vista Ultimate Extra
• Run High-Definition Video as a Wallppaer
• Uses .MPEG/.WMV as content

Windows DreamScene Potential Content:

NASA - Multimedia - High Definition Video Gallery

Stardock DeskScapes at a glance:

The first enhancement is a new program called DeskScapes.  DeskScapes extends DreamScenes to support dynamic content (i.e. videos are pre-rendered).  With dynamic content, you could have your wallpaper change based on weather, time of day, or news.  Or you could just have some cool Direct3D "stuff" that runs (like one of those fish aquariums running as your wallpaper). 

• Extends Windows DreamScene to support Dynamic/Live content
• Adds support for the .Dream format
• Displays author info/URL in the desktop background dialog
• Supports triggers (change videos based on time, weather, etc.)
• Is only available for Windows Vista Ultimate Users
• Is free

Stardock DeskScapes Content:

http://dream.wincustomize.com/index.aspx

http://www.wincustomize.com/skins.aspx?libid=50