1. To begin installation of the Sophos Anti-Virus Client on your Mac, verify that you meet the system requirements (Mac OS X 10.4+), and have downloaded the proper installation package (.dmg file) from the Support Site and double-click to begin.
    
2. The first screen you see will offer you the opportunity to remove any existing Symantec Anti-Virus software.  It is a good idea to check if you're not sure:

3. Once you have confirmation all Symantec Anti-Virus products have been removed, double-click the icon titled "Sophos Anti-Virus.mpkg" - the installation process will begin.  Select "Continue":

4. Next, you will see the release notes for the version of Sophos you are installing.  You will also have the opportunity to print these if you like.  Select "Continue" to proceed with the installation:

5. Next, you will be required to select the hard drive you would like to install Sophos to.  Highlight the drive and select "Continue":

Note: You may receive a message stating, "This package contains a program that determines if the software can be installed.  Are you sure you want to continue?"  You should select "Continue":

6. The screen that follows verifies the installation point.  If this location is correct, select "Install" to proceed:

7. You may be prompted to enter your computer password to begin the installation process; key in your password and select "OK" to continue:

8. Once the installation begins, you will see several messages referring to what is being done to your system.  A status bar near the middle of the messaging window will give you an idea of how fast the installation is running, and how much time is left.  Once the installation has completed, you will receive a message stating, "The software was successfully installed".  Select "Close" to finish the installation: