As a user and developer, you would have surely heard about Drupal, a free and open source Content Management system (CMS) that has great developer network and is free and most secure too. All said and done, if you decide to make the transition from your existing CMS to Drupal, you would surely want to understand the steps to be taken, the cost involved etc. before you take the plunge. If the right kind of homework is done prior to migration, your team will be better prepared for the change and will also keep the migration costs down.