To disable file sharing in NT version 4, go into Control Panel, double-click on Services and locate the Server service. Click on the Stop button and, if you're asked, agree to stop any other services on which this depends. Even after taking these basic precautions, you could be vulnerable to attacks that could lock up your machine. Until the cable networks start protecting your machine by default, you really need a firewall, sometimes called a packet filter. A firewall acts as a network sentry, protecting your machine and advising you of misuse.
Firewalls can be software or hardware.
Each firewall package takes a different view in its approach to security, so check the specifications and talk to people who use software to get an idea of what you want to try. When you find one you like, it's a good idea to see if there's a free trial available. You can test the technical support, as well as learn what the firewall is doing and how it's protecting you. After a lot of research, I chose a hardware solution for my home office. It allows up to five PCs to sit behind the firewall and share the static IP address assigned to me by WorldWind.