Just a quick tip. I think a lot of people are now using utilities like Simplescript to install Joomla on their domains, instead of FTP uploading. Simplescripts and similar utilities automatically chmod the configuration.php file to 644 (unwritable), whereas a manual upload and install leaves the file at 755.
You can't make ANY changes to files chmod to 644. It's confusing if you use Cpanel, because Cpanel opens the file, and seemingly allows you to make changes. If the file IS 644 though, and you read the resulting message after save in Cpanel, it does NOT say the file has been saved. It gives an error message. Read your messages carefully.
Make sure any file you need to change is 755 first. Make the changes. You can then switch it back to 644.
Then again, Simplescripts also automatically sets $live_site = ''; as well, so that setting shouldn't be a problem unless (in the case of using Simplescripts install), it has been manually edited to begin with. Or is there a way to change that in Joomla Admin panel? Not sure.