I know I did not run any extra wires to my PC. It is connected to the AC Ground via the power plug and an Ethernet switch via LAN cable. We know Ethernet works fine with out running extra ground cables because it is used this way in millions of situations. I think the concern for careful grounding is more important if you are directly connecting to the PC via Parallel Ports. I don't remember exactly what I did with the ground connections on the BOB but probably connected them to the chassis ground of the Mill.