Find Out If Your Computer Is Secretly Connecting to the Web

If you are trying to track down why your computer is running so slooowwwly, try using this simple DOS command from Digital Inspiration to uncover a possible problem:

• Type cmd in your Windows Run box.
• Type "netstat -b 5 > activity.txt" and press enter.
• After say 2 minutes, press Ctrl+C.
• Type "activity.txt" on the command line to open the log file in notepad (or your default text editor)

Or
Use TCP View from SysInternals

As found on LifeHacker:
http://.../find-out-your-computer-is-secretly-connecting-to-the-web