agile

We do. First, let me clarify a few assumptions I'm making.

1. If you're using a tool like CaseComplete, I'm guessing you're looking to evolve a user story into something a bit richer.
2. Agile Project is a fairly loose term. So I'll assume you're looking to deliver working software sooner, rather than later – in smaller increments – and user stories/use cases will be as a unit of work.

Here's a short article that talks about evolving from user stories into use cases in a way that works well with CaseComplete:

http://blog.casecomplete.com/post/Agile-Use-Cases-in-Four-Steps.aspx

In the agile world, the way to define acceptance criteria is to through specific tests. This plays well into the Show Testing Procedure feature of CaseComplete. You can define very clear tests for a use case and its alternate scenarios. When the software can function in a way where the tests pass, the use case can be considered complete.

Let me know if this helps.