If you have just upgraded to Windows 7, you might notice that you no longer see any adapters listed in your Select Networks selection. There is a very simple way to fix this problem.
First run CMD as administrator. If you have not done this before, you can use the search option in the start menu to find CMD. Then right click it and select "Run as Administrator". Now type "nmconfig /install" and enter. This will re-bind the Network Monitor Driver to the adapters. Next time you run Network Monitor, the adapters should show up again.
For more information, please see this KB article.