VB.Net - Syntax

Dim oResult As System.Windows.Forms.DialogResult 
oResult = Windows.Forms.MessageBox.Show("This is a question ?", 
                                        "Message Box Caption", _ 
                                        Windows.Forms.MessageBoxButtons.YesNo 
If (oResult = Windows.Forms.DialogResult.No) Then 
End If 

The result is passed back as a DialogResult enumerated value

Microsoft.VisualBasic.MsgBox

Microsoft.VisualBasic.MsgBox(prompt As Object, _ 
                          [ buttons As Microsoft.VisualBasic.MsgBoxStyle = MsgBoxStyle.OKOnly ], _ 
                            [ title As Object = Nothing ], _ 
                                    As Microsoft.VisualBasic.MsgBoxResult 

When you have a look inside it is easy to see which method should be used to display a message box.
It appears that Microsoft.VisualBasic.MsgBox() does some exception check and then passes the call onto System.Windows.Forms.MessageBox.Show() this then does pretty much the same exception checking and the passes the call onto System.Windows.Forms.SafeNativeMethods.MessageBox() which is itself a wrapper for a win32 API call to user32.dll.

Microsoft.VisualBasic.MsgBoxStyle 

Microsoft.VisualBasic.Interaction.MsgBox()