CentOS is the easiest to use FSF GNU GPL operating system you can find

• Graphical Installer
• Graphical Login
• Online Updates
• WindowPrint and ScreenPrint functionality
• A WebBrowser, EmailClient and OfficeApplications come pre-installed
• Admin GUIs for NetworkSettings and PrinterSettings
• You are always prompted for the root password whenever it is required

Documentation

• It is easy to find and buy books on Red Hat RHEL 4 and CentOS 4