By default, Windows explorer in Vista does not show file extensions. If you want to show file extensions in Vista Windows Explorer, from an Explorer window select the "Organize" -> "Folder and Search Options" from the menu list. Once the Folder Options panel open, select the "View" tab and scroll down the entry called "Hide extensions for known file types". If you uncheck the box next to this and then click the "Apply to Folders" and this preference will be set to show file extensions.