Creating a project in TFS fails

Question

I'm attempting to create a new project in TFS 2008. The process errors out with the following message:

The content databases in this cluster are full. You cannot add more Web sites until you change the content database Web site capacity settings or add more content databases.

I want a new content DB created for each TFS project, and I can't find how to tell TFS "go ahead and create a new content DB for this project."

Surely I'm not supposed to create a content DB manually in central admin, and if so, where do I tell TFS "here's your content DB for this project"?