TortoiseCVS lets you work with files under CVS version control directly from Windows Explorer. It's freely available under the GPL.

CVSNT Server stores a copy of your files and documents and tracks all of the changes to it over time. Based on CVS which for fifteen years was the most popular versioning tool, CVSNT has added five years of development to build the best modern versioning solution. With 1.4 million downloads in the last year it's probably right for you too.