There are many tools to use for windows
Programs: TortoiseCVS http://www.tortoisecvs.org/
Another tool but not for free its Free Commercial Usage: Free for 30 days trial (fully functional) http://www.componentsoftware.com/products/cvs/download.htm#
Non Famous :
http://www.twobarleycorns.net/tkcvs.html
http://www.jspwiki.org/wiki/CVSClientsOnWindows
http://www.ifm-services.com/people/jamesk/papers/cvs/cvs-win32-client.php