Caputure Window Text

Its a simple requirements. Functionality is important than the appearance and presentation. I need a tool to list the applications running, when i select any application window name from that list, it should caputure the contents (text) form that application screen to a text file. If that application is MDI application all the opened childform's contents should be saved into the text file. The code should be in either C#.NET or VB.NET or in VB6.0 Bid only if you can deliver me in few days or if you have anything else handy.