Drupal is the best php, mysql or postgresql, CMS system.
Version to use: 4.6.5 (4.7 is due "soon").
I've used a couple of CMS systems over the years, including a home brewed one and I've tested even more of them. After trying out all of these, my feeling is that Drupal.org.
You may have noticed that our family website is based upon it.
I've also built the <a href="http://www.bakerneighborhood.org" title="BakerNeighborhood.org Baker Historic Neighborhood Association Baker District Denver, Colorado>Baker Historic Neighborhood Association website using Drupal.
And I'm working on a group travel blog based on Drupal. It's a great system, highly flexible, fast. Happiness.