I am thinking of using ClamAV on Digital Signage displays running XPe.

I need it to update and scan silently on every shutdown (daily)

What is the best way to do this?

You said Clam AV. This is the ClamWin forum. If you really meant ClamWin, perhaps you could set up something in Task Manager. I would set updates to hourly--that should be good enough, and they are silent anyway.

Regards,