Hi Jodie,
I wasn't sure if you noticed it on the start page in the software, but we do have a post on using CaseComplete in an agile manner - specificially, use cases in the backlog - on our blog. As a good starting point (if you haven't read it yet), Matt discusses some of the pros and cons of use cases in an agile environment in the post, and there is some further discussion in the comments on that page.
http://blog.casecomplete.com/post/Use-Cases-in-an-Agile-Backlog.aspx