TCPView is a Windows program that will show you detailed
listings of all TCP and UDP endpoints on your system,
including the local and remote addresses and state of TCP
connections. On Windows NT, 2000 and XP TCPView also reports
the name of the process that owns the endpoint. TCPView
provides a more informative and conveniently presented
subset of the Netstat program that ships with Windows. The
TCPView download includes Tcpvcon, a command-line version
with the same functionality.
TCPView works on Windows NT/2000/XP and Windows 98/Me. You
can use TCPView on Windows 95 if you get the Windows 95
Winsock 2 Update from Microsoft
http://www.sysinternals.com/ntw2k/source/tcpview.shtml