The upcoming Visual Studio 2005 release comes with a choice of source control mechanisms:
VSS 2005, the new and improved VSS; and Team Systems which takes the development effort
to a totally new level, with integrated test tools, project management capabilities
etc. This article discusses the relative merits and the criteria for choosing one
over the other.
(On a side note, it talks about the relative cost too, but doesn’t seem to include
the extra Windows, Sharepoint and SQL Server licenses to run VSTS)