Yes, the periodic scripts run. The system checks at boot, and runs those scripts in the background if the system has gone past its usual time/day to run that periodic task.
If you prefer to run them manually, then they can be run at any time through the terminal, or using one of the many maintenance utilities. OnyX is a well-known example.
DeltaMac, Thanks again. You have been a big help in getting this new Mac Pro set up and
running. I downloaded Flip4Mac, and Perian, at your advice, and they open most PC
attachments, but a few, Those that say"Mime-Type Application/Octet-Stream".