Dyna-Portal or Open Source?

We have 5 unique web properties and are looking for a single solution to manage all of them. Currently we are using css, a php directory, and straight old dynamic html. We offer an industry directory with 3 levels of paid advertisers/subscriptions, a social site for owner/operators, and a new developer site that includes a wide variety of paid services and products. We would like to run an 'ad network' across all of them and be able to share various forms of content between them all as well. Podcasting, videos, subscriptions, eLearning, resume postings, user posts, forums, advertising, the works. I am totally ignorant to the open-source option and wonder if someone could tell me if Joomla, Drupal or Plone would work for something like this? Your replies are appreciated.
-Smiler

 

Joomla and other open source CMS systems work well. But be careful to always backup your files and databases because they are prone to the odd security attack and you could lose all of your sites in one go.

 

Thank you for your reply.