Found it :
HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\WindowsFirewall\DomainProfile
\EnableFirewall=0 (DWORD data type)
HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\WindowsFirewall\StandardProfile
\EnableFirewall=0 (DWORD data type)
From http://www.microsoft.com/downloads/details.aspx?FamilyID=4454e0e1-61fa-447a-bdcd-499f73a637d1&displaylang=en
Sorry, I did assume that you were turning them off through the service. In your report, you might want to include conditions on both the registry setting and service. It is possible for the key to be set but the service to be stopped.