All Internet Routers have to have the following settings:
Do not turn on DMZ.
Set Virtual Serving for the following ports:
Ports 8000-8050 (TELNET) or whatever ports they use
5800, 5900 (VNC)
515 (LPR) do not setup if not using
1603 (ODBC) do not setup if not using
25017 (ActiveFax) do not setup if not using ActiveFax over the Internet
Also, make sure there is an Administrator password.
Make sure you install the free version of AVG (www.grisoft.com) at a minimum.