How to install sub-version on Linux:
Installing GIT
A guide on installing git on a server
http://www.kernel.org/pub/software/scm/git/docs/howto/setup-git-server-over-http.txt
Git GUI
Overview of GIT GUI clients:
http://theappleblog.com/2009/03/10/using-git-with-os-x-6-tools-to-get-you-up-and-running/
Branching and other
http://www.codinghorror.com/blog/2007/10/software-branching-and-parallel-universes.html
Source control systems
In order to select a good source control system for your organization, please make sure to read following articles. If you need assistance in deciding, we can be of help.
Warning: There is a difference in between Source Control, Version Control, Lifecycle management system, … make sure not to mix those up.
Now the article (gone already).
Another good source is Forrester research.