If, like me, you connect to many different networks (I'm a network consultant), then you probably find OS X's ability to create different locations a most useful tool. But how to back them up to reinstall or tranfer to a new machine? After a long search, eureka! They're all in one single file:
/Library/Preferences/SystemConfiguration/preferences.plist
All you need to do is copy that file and restore it on the new machine.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20060919021831172