Copy the below code to a notepad and rename as a batch file. e.g. InstallSAV.bat

@ECHO OFF
REM — Check for an existing installation of Sophos Anti-Virus
if exist “C:\Program Files\Sophos\Sophos Anti-Virus\SavService.exe” goto _End
REM — Deploy to Windows 2000/XP/2003
\\servernamehere\SophosUpdate\CIDs\S000\SAVSCFXP\Setup.exe -s \ -user domain\username -pwd passwordhere -mng yes
REM — End of the script
:_End

Replace ‘servernamehere’ in both locations.
Replace ‘Domain\Username’
Replace ‘passwordhere’

Always test on one machine before pushing out to all.