If you want to use eye catching windows 8 themes with previous versions of windows, so here is how. The theme directory at official windows site windows.microsoft.com hosts some beautiful themes for your Windows desktop. There are lots of themes , but some newer themes are however compatible only with Windows 8 machines, like these dual-screen panoramic images.
The Windows theme files have a .themepack extension but the Windows 8 specific themes are distributed as .deskthemepack files. but we can still extract the wallpaper backgrounds of these Windows 8 specific themes and use them on older Windows PCs Internally, we can extract these archive format using the free 7-zip utility.
First we Install the 7-zip utility on PC and then download any of the .deskthemepack files from the Windows Themes gallery.
Rename the theme file and change its extension to .7z (you can just append .7z to the file name). Now right-click this files and extract the included wallpapers to your desktop.
Now either use these background individually or put them in one folder and then open Desktop Background under the Control Panel.