You are running netstat on the local machine. What's more important here is ACTIVE CONNECTIONS (established). If you want to get a more realistic idea of how secure you are, run a port-scanner from the internet. Just because your PC is listening on a port, doesn't mean there's any way possible for something outside your LAN to get wind of that and establish a session. If you have a typical SOHO router, NAT prevents that, unless you circumvent it.