Trying to make Windows Vista Explorer show previews for more file types used to be a pain and involved playing around with the registry. At www.mintywhite.com, we like to do things the easiest way possible, and that’s exactly what we’ll do with this hack.
The PreviewConfig utility for Windows Vista is extremely simple to use. Once you open the program, a list of filetypes populates in the left-hand pane, and on the right, you may select the preview type. And… you’re done.
Selecting media will use Windows Media Player to render a preview for the file type. Files like .mkv (an alternative to .avi - primarily used for HD video) can be decoded by Windows Media Player with the right plugins, but will not render automatically in Windows Vista. Selecting plain text will show a text preview for the file.