Default Notepad++ to XML language sytnax highlighting for .config files

On the Notepad++ menu bar, click "Settings" -> "Styler Configurator..."

- Under "Language", select "XML"
- Under "User ext", type in "config".  While we're at it, let's also type in (space delimited) "aspx", "ascx", and "master".
- Click "Save & Close"

That's it!  Now when you view config files, ASP.NET pages, user controls, or master pages in Notepad++, you'll get syntax highlighting.

More about this here... http://www.mattblodgett.com/2007/11/notepad-tip-syntax-highlighting-for.html