Конвертирование *.fb2 в *.txt

Dim Txt As String = IO.File.ReadAllText("1.txt", System.Text.Encoding.Default)
        Txt = Txt.Replace("<p>", "") : Txt = Txt.Replace("</p>", "")' и т.д.
         IO.File.WriteAllText("1.txt", Txt, System.Text.Encoding.Default)

    Public fd2 As New XmlDocument ' New XDocument
 
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        fd2.Load("D:\Inst\BooksReader\432021.fb2")
    End Sub
 
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Dim str As IO.StreamWriter = New IO.StreamWriter("D:\Inst\BooksReader\123\000\432021.txt")
        For Each oi As XmlNode In fd2.GetElementsByTagName("body")(0).ChildNodes
            If oi.HasChildNodes Then
                For Each op As XmlNode In oi.ChildNodes
                    If op.HasChildNodes Then
                        For Each ol As XmlNode In op.ChildNodes
                            str.WriteLine(ol.InnerText)
                        Next
                    Else
                        str.WriteLine(op.InnerText)
                    End If
                Next
            Else
                str.WriteLine(oi.InnerText)
            End If
        Next
        str.Close()
    End Sub