How to Configure Software Update on Lion Server
As one of the final touches on your Lion Server installation, open System Preferences by clicking the Software Update icon and edit the Software Update settings. The default settings aren’t exactly dangerous, but they are more appropriate for a client computer than for a server.
By default, Software Update is set to check for updates weekly and to download them. Don’t worry, it doesn’t install, download, and update; it brings up a dialog asking you if you want to install the update. To prevent this, in the Software Update Preferences window, leave the Download Important Updates Automatically check box turned off.
You might also want to deselect the Check for Updates check box so that the server isn’t regularly checking for updates by itself. Best practice is to use the Check Now button to manually check for updates or simply launch Software Update. You might set up a repeating calendar reminder in iCal to remind you to check once a month or so.
If you want to update your server to a version later than what you have but earlier than the latest, you can. Apple offers older updates at its website, which you can download with a web browser.