CVS is a source code control system/repository. Most people using .net use visual source safe or pvcs. PVCS is more corporate.
PVCS and CVS in visual studio require plugins. igloo was the first, and is probably the most commonly used one for cvs. There's been several others that came out later that may/may not be better.
If you're checking out cvs on freebsd, you may also want to look at Ant, which is a make-like build tool that's gaining a lot of popularity - lot cleaner to use than make.
Edited by dpyers