Server :: VERY Simple CMS Needed For Intranet

I work for an organization with a few hundred employees. We need a very simple CMS for posting basic organizational documentation such has step-by-step instructions, as well as pdf and MS Office documents.We would prefer something that would organize content hierarchically, so we can structure the info into departments and functional areas. A MySQL or similar database is preferred, but flat file is okay as long as it does not limit content/structure too much.We would probably have about 15 to 20 content authors/editors. No workflow, authentication (except authors/editors) or secure content areas are required.

The only limitation would be that the content could only be accessed from a particular range of IPs. (I assume that would be set in Apache.)