List available machines on the network

I need to provide the user with a dialog to choose a folder on any machine accessible on the network.

In Windows Explorer you can navigate to My Network Places\Microsoft Windows Network and get a list of available domains/workgroups and under each of these a list of available machines.

Is there any way to access this information programatically I am thinking of a dialog to let the user choose a domain and then list the machines available. After a choice of machine I would list the folders available on this machine.

Where should I go in the .NET namespaces to get access to this

Thank you

Lars