If your opinion of your staff is that low then they have no reason to be security aware for you and the attacker has already won.
If you really want to understand the need for staff security training read this: http://www.amazon.com/Ghost-Wires-Adventures-Worlds-Wanted/dp/0316037702/ref=sr_1_1?ie=UTF8&qid=1317745637&sr=8-1

With uneducated staff, all other countermeasures are pointless but for the script kiddies.