Did your PC restart without warning while you were trying to work on an important project? Did it say it was restarting for Windows Update?  You can conrol the behavior where Windows restarts for windows update as follows:

1. Right click on the Taskbar, choose Properties.
2. The Taskbar and Start Menu Properties window will open.
3. Under Notification area click the Customize button.
4. Set "Windows Update"  to "Show icon and notifications".
5. Click OK.

You could even check "Always show all icons and notifications on the taskbar".

In Windows 7 Professional and Ultimate, you can change the notification behavior and timeout using Group Policy. Click the start menu and type gpedit.msc. Right click gpedit.msc, choose 'Run as administrator'. Agree to the UAC prompt.

1. Navigate to the following group policy:
   Local Computer Policy->Computer Configuration->Administrative Templates->Windows Components->Windows Update
2. Open "Re-prompt for restart with scheduled installations".
3. Click the radio button for "Enabled".
4. Edit the field for the timeout Under "Wait the following period before prompting again with a scheduled restart (minutes).

The help description says "Specifies the amount of time for Automatic Updates to wait before prompting again with a scheduled restart". The maximum is 1440 minutes.