I want to start Software Update Server to run from a specific time night.

Firstly, copy the following into the Applescript Editor and save it as an application.

tell application "System Events"

tell application "Software Update" to activate

delay (1)

keystrokereturn

end tell

Then set up an alarm in iCal for the time you want it to work, and choose to 'Open file', selecting this Applescript application.

Before you go to bed, run Software Update and if it has any downloads for you, select them but don't initiate them. Just leave it open and hopefully iCal and the script will do the rest. I should test it at a time you can watch it run first time round, just to make sure it works (I don't have any downloads so i was only able to test it by quitting Softeare Update).

And here's a further idea, so you don't have to run the check manually. Copy this script into the AppleScript Editor and save as an application:

tell application "System Events"

tell application "Finder" to activate

clickmenu item 3 of ((process "Finder")'s (menu bar 1)'s (menu bar item 1)'s (menu 1))

end tell

Now set up and iCal alarm at least ten minutes before the other one and choose this Applescript as the alarm. That should open Software Update and run a check. Then if nothing is found the second alarm should quit it, if there are downloads they should be downloaded - but again check it first time while you can watch it as I can't test this.