Here's a bit of a "plug" for some open source SCM tool offerrings ...
For those CVS users who don't already know about Subversion I urge you to take a look. Subversion was designed to be a next-generation replacement for CVS that has a lot of the same basic syntax and development model while fixing or updating most of its well known shortcomings.
Another spiffy open-source project that integrates with both CVS and Subversion is Trac, which provides simple but powerful defect/issue/enhancement tracking (DIET) using a Wiki-web interface, and readily integrates with both CVS and Subversion to add collaborative, low-friction request/activity tracking to your version control and can be used to track change-sets in the version control tool and associate them with change-tasks/requests in the tracking tool.
Using Trac with Subversion can help "subtract" a lot of the tedium of traceability from your day-to-day work and give more "traction" to your development efforts. So, in a way, Subversion plus Trac gives SubTraction :-)