If the OpenACS file manager is like the original ACS version, there is a configuration parameter for whether or not the file manager uses version control or not. Automatic use of CVS is one of the major things I like about file-manager so I would recommend using it. CVS can be found at http://www.cvshome.org/. Don't know how hard it is to make; it was either on the system (like my RedHat box) or I just copied a working binary from one system to another. One thing to double check - you will need have a version >= 10. Think it is called Halibut if I remember.