Shared Resources – good or bad?

We have a combination of operating systems (Windows 98SE and Windows NT4.0 SP6 in our company. We often see users that have set up shares on their local PC rather than use the built in secuirty in our network. Most of these employees don’t even realize that anyone on the network can access and change their local PC’s drive(s). Does anyone now of a simply worder document that will expain teh good, the bad and the ugly about sharing.