Open Source Version Control

Open Source Version Control (CVS)
CVS (Concurrent Versions System) is a version control system, an important component of Source Configuration Management (SCM). It is used for collaboration and version control. Using it, you can record the history of sources files, and documents. It fills a similar role to the free software RCS, PRCS, and Aegis packages. reference

WinCvs is not a replacement for CVS. WinCvs is a GUI front-end for a CVS commandline client.
Sophisticated graphical user interface helps to utilize full power of CVS for experts and quickly learn basics for beginers. For download and more info:
http://www.wincvs.org/
It is required to install Python to run the wincvs:
http://python.org/
For documention check this link:http://cvsbook.red-bean.com/cvsbook.html
Also check out this website for more info and download: http://ximbiot.com/cvs/wiki/ Quick download link: http://ftp.gnu.org/non-gnu/cvs/

CVSNT
Difference between WinCvs and CVS
WinCvs is not a CVS server! It can be used to run the client in :local: mode, so you could manage a single-user repository on your local machine all from within the WinCvs GUI, but as soon as your repository is going to be accessed by more than a single local user and/or from a different machine, you should look for a "real" CVS server. Currently the most advanced is the CVSNT project, which is available both for Windows and *ix operating systems. The "original" CVS project is maintained at http://www.cvshome.org/, where you could also find CVS servers and documentation for a plethora of other operating systems as well.
Difference of CVSNT with SVN

Subversion
The goal of the Subversion project is to build a version control system that is a compelling replacement for CVS in the open source community.
TortoiseSVN is a really easy to use Revision control / version control / source control software for Windows.