For v8.0, the registry key is changed to "HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Adobe\Adobe Acrobat\8.0\FeatureLockDown\cDefaultLaunchAttachmentPerms". "tBuiltInPermList" is the REG_SZ value to change. 

For v9.0, the registry key is changed to "HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Adobe\Adobe Acrobat\9.0\FeatureLockDown\cDefaultLaunchAttachmentPerms". "tBuiltInPermList" is the REG_SZ value to change.