Version Management System: Subversion ( http://subversion.tigris.org/ ) is good.
Subversion has problems. A distributed sollution like Git is probably better, once you know how to work with it (I don't, but it's on my Todo-list). For more info on Git, compared to subversion, check this vid:

http://www.youtube.com/watch?v=4XpnKHJAok8

If you are not comfortable with a command-line interface, you should check the GUI front-ends (like TortoiseGit).