TortoiseCVS lets you directly check out modules, update, commit and see differences by right clicking on files and folders within Explorer. You can see the state of a file with overlays on top of the normal icons within Explorer. It even works from within the file open dialog. You can perform tagging, branching, merging and importing, and you can go directly to a browser web log (using ViewCVS or CVSWeb) on a particular file.
There are some CVS things that you can't do with TortoiseCVS - have a look at the feature requests database. The GPL license lets you improve TortoiseCVS, as long as you make any changes to the source code available. If you would like to help implement some features, please see the development section.

The license of this software is Free Trial Software, you can free download and get a free trial.