Brian, that's what that query would do - find completed
Tasks. If I were trying to query for completed
Stories, I would query on the ScheduleState field, not State.
Are you trying to list stories with completed tasks? Or are you just trying to list tasks?
I would definitely recommend creating a custom page (
https://help.rallydev.com/create-custom-pages)then adding the Custom List app (
https://help.rallydev.com/custom-grid). It makes it really easy to filter for what you're looking for on the front end. In the app's setting (gear at top-right), you can set the kind of work item that you want to see, whether it's Tasks, Stories, Defects, Portfolio Items, etc. Using Advanced Filters from the app, you can really drill down to specifically what you're looking to show.
I just recorded a screen capture showing how set it up showing Tasks that are completed:
http://screencast.com/t/MTKR2UxiQIf you do want to show
Stories with Completed Tasks, I believe if you filter on Task Status = COMPLETED (using those front-end filters), it will only show the stories where
all tasks are completed, if that makes sense.