• Windows 7 components are designed to be modular and selectable
• The files necessary to install Windows 7 or end user applications can be compiled into a single WIM file acting as a library. The files used to install the end user application are considered one image. The files used to install Windows 7 are a second image. These separate images can be combined into one image file to make it easy to distribute both Windows 7 and applications to new computers.
• The WIM format offers many benefits when compared to other popular imaging software:
• The contents of the image files can be edited, added to, and deleted directly.
• Updates can be applied directly to the images without first having to install the image on a computer.
• The contents of the image files are typically compressed to save space.
• The WIM format supports single-instance file storage. A file can be referenced in multiple images, but it is only stored once in the image file.
• WIM image files can be deployed from many media types (such as DVD, network share).
• One image file can be used on a variety of computers.
• WIM image files can be used with scripted installations.

For more information about the Windows Imaging Format (WIF), visit: http://technet.microsoft.com/en-us/library/dd799284(WS.10).aspx