Drupal development team has released Drupal 5.2 on July 26, 2007. It fixes two security vulnerabilities, so it is highly recommended that you upgrade as soon as possible. Many Drupal installations often contain extra Drupal modules, and almost always the also contain local customizations.
Question arises: how to upgrade your Drupal installations timely, safely, with confidence that none of your local customizations are lost; without need to remember each line that was edited and re-applying those edits to new version and without need to drastically change your workflow (very little discipline is needed actually).
This detailed guide walks you through the import of the source code, import of the Drupal modules and making the upgrades to the installation (drupal, drupal-and-modules and drupal-production) as well as how to resolve conflicts that might come up.