[s_henry_paulson]

Except for MAC filters aren't relevant to this situation at all. Private VLANs, however, are.

A VLAN would keep these computers on their own network, and firewalls could be set up on the network side to prevent this stuff from happening.

A MAC filter would do nothing in this situation, because you are using their computer. Even if you had a MAC filter, these computers would be white-listed anyway.