In tip 7632, I described how to configure Automatic Updates using group policy.
In a non-Active Directory environment, you can configure Automatic Updates using the registry. The key path is:
NOTE: You must manually add any missing sub-key.
The Value Names that correspond to the group policy settings are:
Value Name Data Type D e s c r i p t i o n NoAutoUpdate REG_DWORD 0, the default, Automatic Updates is enabled. 1, Automatic Updates is disabled. AUOptions REG_DWORD 2, Notify for download and notify for install. 3, the default, Auto download and notify for install. 4, Auto download and schedule the install. ScheduledInstallDay REG_DWORD 0, Every day. n, where n is a number from 1 (Sunday) through 7 (Saturday). ScheduledInstallTime REG_DWORD n, where n is the time of day in 24-hour format, 0-23. UseWUServer REG_DWORD 1 uses a server running SUS (Software Update Services). RescheduleWaitTime REG_DWORD m, the time in minutes, 1-60, to wait, after startup, for a missed update. NoAutoRebootWithLoggedOnUsers REG_DWORD 1 does NOT automatically restart the computer if a SUS SP1 client is logged on.