If you're running any TCP/IP services (such as WWW service, FTP service, POP3/SMTP services, or even just NetBIOS over TCP/IP) on your computer, you may want to find out who's connected to your computer and from where at a given time. This information is easy to obtain using NETSTAT command.
Go to the "DOS Prompt" or "Command Prompt"
Type
NETSTAT <number of seconds>
For example, if you want to redisplay the TCP/IP connections every 10 seconds, type:
NETSTAT 10
Press ENTER