How do you expect this to work Raphael?
App Inventor apps cannot communicate using TCIP, AI does not have a TCIP client or server component.
Can your Visual Basic application receive Bluetooth information. If so, AI can talk to it.
There is probably no way to directly exchange data directly between your app and your Windows program. You might send a text file as an email from your AI2 app and use your Visual Basic app to 'read' the text file. You could post data to a FusionTable and read it back from your Visual Basic program. You could send data to a Google Drive and retrieve it using you Windows program.
Consider how your Win program would exchange data with other Windows apps and that will give you a clue as to other possibilities and the appropriate protocols. Part of what might be possible depends on what your Windows program does and how it uses data. Exchanging csv files might be possible because both operating systems share that protocol.
Others might have other suggestions.
Good luck.
Regards,
Steve