We are team of few Delphi developers who have been using VSS since years (I know it\'s a pity), but we don\'t use any of the advanced features of VCS, so it was working fine
Team Coherence is a good choice. They just released a new client, so it looks like support is alive and well.
Our Delphi team recently (last year ) upgraded from VSS to Perforce which is an absolute joy to work with. It is expensive but is well worth it. It makes source code control one of the tools of your trade rather than a chore or a hinderance. It has good GUI tools, a great commandline when required and there is a free Delphi IDE integration available online.
It does take a bit of getting used to, but is worth putting in the effort when you get to the point where you can create branches with abandon and merge changes knowing you dont ever have to worry about losing any changes ever. Its fast, efficient and a pleasure to use.
You should at least take a look at JVCS. It integrates with the Delphi IDE, it's written in Delphi and is open source, and you can choose from a number of databases including Firebird to store your archive in.
There is Team Coherence (http://www.teamcoherence.com/) which is written in Delphi and integrates with the IDE very well. We still use it. Support is patchy though.
Most people seem to be moving to SubVersion though.
Unless you are directly heading to SVN (which I wouldn't recommend, if you're thinking on something free go to Git or Mercurial) check Plastic SCM. Find a couple of Delphi specific tutorials here:
http://codicesoftware.blogspot.com/2008/06/branching-and-merging-with-delphi-part.html http://codicesoftware.blogspot.com/2008/06/branching-and-merging-with-delphi-part_02.html
Just use SVN and an excellent TortoiseSVN client which integrates with the Windows Explorer.
P.S. Found this question: What is the best set of tools to develop Win32 Delphi applications? and this Delphi IDE/TortoiseSVN integration tools in one of the answers: http://delphiaddinfortortoisesvn.tigris.org/