OCModShop has a new guide on how to enable hidden Themes on Windows 7
Windows 7 configures a handful of themes upon initial installation, but did you know that there are several more that are not installed by default? Microsoft has set up Windows 7 to only install themes relevant to the language and location you specify during the installation script, but you can easily access and install more themes that Windows doesn't think you want to see.Enable Hidden Windows Themes