CVSNT
TortoiseCVS
OpenCVS

CVSNT Installation for Windows
cvs-mailcommit is a helper application to CVS to help people keep track of CVS repositories via mail. It is hooked into the CVS system via the CVSROOT/loginfo file. It will read modification information from CVS via stdin and require version information via the commandline.

Subversion
TortoiseSVN
AnkhSVN is a Subversion Source Control Provider for Microsoft Visual Studio

Subversion 1.6 Quick Reference Card
Version Control with Subversion free (e)book.

Bazaar is a distributed version control system that Just Works. While other systems require you to adapt to their model of working, Bazaar adapts to the way you want to work, and you can try it out in five minutes.

Mercurial a fast, lightweight Source Control Management system designed for efficient handling of very large distributed projects.
tortoisehg/stable GUI management tools.
Mercurial binary packages for Windows and Mac OS X

Git
Steve Bennett Blogs - 10 things I hate about Git

Fossil

Chisel Fossil SCM Hosting. Chisel - All public repositories
SharpFossil - Fossil Windows GUI and C# Library
Fossil User Manual