business modules

The company I work at has chosen Drupal to run the customer support site. I'm wondering if anyone is using Drupal for that use case and if there are some recommended modules that would be appropriate for this type of site.

Here's a sample of things that we'd want to make available to customers (left out core features such as forums):

• FAQ
• Tutorials
• Customer specific views
• Download center
• Knowledge base

Thanks,
Thien