Changing Rights for Role "Contributor"?

I am in the very beginning of planning a website and "misusing" antville as CMS. I have seen examples that encourage me to follow this idea.

But I have one question abou the role "contributor" and the rights included: Is it possible to limit the contributors rights to create/modify and just save articles? The content manager then will check those articles and set them online... Any Ideas? Maybe just creating a special form for contributors without "Publish"-Button?

Thanks in advance...