Just found a nice article on Mike Swanson’s blog about Windows 7 Theme Packs. Windows 7 introduces theme packs, which are .cab files that contain all of the necessary assets to implement a theme, including sound files and images.
Download the official Microsoft Theme Packs here
Download the Theme Packs from Mike Swanson here
While in Windows XP it was rather a pain to create your own Themes, it looks like in Windows 7 things have been simplified a bit. Definitely interesting for companies as well to apply their corporate design to their clients.