Consider using Perforce from
http://www.perforce.com/ . Free
projects
are eligible for free licenses. It is so easy to use in comparison to
CVS and much more reliable. There is even an emacs mode ...
I use perforce at work and like it a lot, but - it doesn't scale
particularly well
since the server knows about all of the clients. I suspect that this would
be
prohibitive for a free project that had many repository users.
andy