If you are worried that some programs on your PC are secretly making connections to websites in the background, here's a quick tip that uses a simple DOS command to detect and prevent such suspicious activity:
1. Type cmd in your Windows Run box.
2. Type "netstat -b 5 > activity.txt" and press enter. After say 2 minutes, press Ctrl+C.
3. Type "activity.txt" on the command line to open the log file in notepad (or your default text editor)
The file activity.txt will have a log of all process that made a connection to the Internet in the last two minutes. It will also show which process connected to which website in this time. And not just the web browsers (like iexplore.exe or opera.exe), the log will also show your IM clients, download managers, email programs or any software that requires a net connection.
Scroll though the activity.txt file and look for any process names or website addresses that you are not aware of. If you track one , go to the task manager (or Process Explorer) to find the location of the executable on your computer and eliminate it.