Class ExcelExport
    Public Function export(Byval oRow as Excel.Row) as Boolean
        Try
            Using xlApp as New Excel.Application
                 Using xlBook as Excel.Workbook
                     xlBook=xlApp.Workbooks.Open("meinexcelvorlage.xls")
                     Using xlSheet as Excel.Worksheet
                         xlSheet=xlBook.Worksheets(1)
                         'Hier kannst Du jetzt dem Worksheet die Zeile 
                         ' hinzufügen
                         '...
                         '...
                     End Using
                     xlBook.close(True)
                 End Using
                 xlApp.close
            End Using
            Return True
        Catch
            Return False
        End Try
    End Function
End Class

    '...
Catch ex As Exception
    Return ex
End Try

Dim xlExport as new ExcelExport
xlExport.export(new Excel.Row(...)) '<- hier bin ich mir bei dem Konstruktor 
' der Excel.Row nocht mehr ganz sicher ;-)

Public Function export(Byval oTable as Datatable) as Boolean
    '...
End Function