[drupal-support] moving a site?

hi all - I want to get a Drupal site all up and running in the background, and then switch it to live. If i configure the site on one URL, and then move it to a new URL, is the only change needed in the sites/default/settings.php -> $base_url = or are URL entries somehow written into the DB? the DB connection URL will remain the same. Is there another way to do this? eg can i setup the site in a subdirectory? tx! /dc