HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows\WindowsUpdate\AU
AUOptions
Reg_DWORD
Range = 2|3|4|5
2 = Notify before download.
3 = Automatically download and notify of installation.
4 = Automatic download and scheduled installation. (Only valid if values exist for ScheduledInstallDay and ScheduledInstallTime.)
5 = Automatic Updates is required, but end users can configure it.
NoAutoUpdate
Reg_DWORD
Range = 0|1
0 = Enable Automatic Updates.
1 = Disable Automatic Updates.