Halloween is the annual festival celebrated on 31st October every year. The main feature of this festival is costume parties, ghost tours, pranks, horror movies, ghost stories etc.
Microsoft recently released Halloween theme pack for Windows 7 users to add more flavor to the festival. This theme pack constitutes 15 wallpaper. You can set them as a slide show and set it to change after every 15 minutes.
After downloading the theme (download link given at the end) double click on the theme file. It will automatically unpack and applied. Click on the Desktop background link to check all the 15 wallpapers in the theme pack. You can choose which picture to appear on the wallpaper and time of changing the wallpaper.
This way you can download and use Halloween theme pack by Microsoft. This theme pack is only available for Windows 7 users.