Erwin (3.5) used to be one of my favorite modeling tools.  But alas, support and features tanked when CA bought the tool.  Most of the features are useless in a real development environment. 

I love having a visual diagram, and now just use Visio (Enterprise Architect).  This tool need alot of work also though!

My recommendation, sad to say, is to skip Erwin.  Use Visio and Word, and you will be just as far and at less cost.