If you are wanting to reinstall OS X, but don't want to lose all your location settings, here is the location of the configuration file to backup:
/private/var/db/SystemConfiguration/preferences.xmlTo get at it, open a terminal window and enter the following command:
% open /private/var/db/SystemConfiguration/The folder should pop open in the Finder, displaying (at least) the preferences.xml file. Drag it out of the SystemConfiguration folder to your desired location to back it up. It should make a copy, not move itself, as indicated by the "plus" sign that appears beside the cursor when dragging it out of the folder; if a "plus" sign doesn't appear, hold down "Option" key as you drag it to force a copy. You should not need root privileges to copy the file, as all users have read access to it.
% sudo mv (backup/file/path/)prefereces.xml \Wish I would've known this before I reinstalled my OS thinking my "pay as you go" internet service providers password and login info was safe in my backed up Users folders. Would've saved me time re-configuring my 15 different locations too!
/private/var/db/SystemConfiguration/
Mac OS X Hints
http://hints.macworld.com/article.php?story=20020724084755731