How to: Extract images from a Windows 7 theme file
All the Windows 7 themes downloaded from Microsoft’s official galleries or anyplace else are in .themepack format. This is a compression and archive method proprietary to Microsoft. Some of these themes contain interesting images which you may want to extract.
C:Users(your user name)AppDataLocalMicrosoftWindowsThemes
Note: The folder ‘AppData’ is hidden by default. So once in ‘C:Users(your user name)’ go to ‘Organize’ menu on the top left corner of the explorer, then ‘Folder and search options’. ‘Folder Options’ would open up. Go to the ‘view’ tab. Click on ‘Show hidden files, folders and drives’. This will make the hidden files and folders appear. Find folder ‘AppData’ and continue.