Find Replace text inWord from Vb.net

[Zeljko]

Searching this group i found interesting solutions and couple of problems.
I need to search from VB.net, text in Word and replace that text with replacement text. I need to replace 500+ words!
-VB.net 2005 express
-word 2003
-PIA reference added

Imports Word = Microsoft.Office.Interop.Word
 
Public Function DoFindReplace()
        Dim oWord As New Word.Application
        Dim oDoc As Word.Document
        Dim sFind As String
        Dim sReplace As String
 
        oDoc = oWord.ActiveDocument.Content
        Dim rngRange As Word.Range = ActiveDocument.Range 'Problem: Not Declared
 
        With rngRange.Find
            .ClearFormatting()
            .Replacement.ClearFormatting()
            .Text = sFind
            .Replacement.Text = sReplace
            .Forward = True
            .Wrap = Word.WdFindWrap.wdFindContinue
            .Format = False
            .MatchCase = True
            .MatchWholeWord = True
            .MatchWildcards = False
            .MatchSoundsLike = False
            .MatchAllWordForms = False
            .Execute(Replace:=Word.WdReplace.wdReplaceAll)
        End With
    End Function
 
    Private Sub subsubTran_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles subsubTran.Click
        Dim oWord As New Word.Application
        Dim oDoc As Word.Document
        Dim path As String = Me.TextBox1.Text
        oWord.Visible = False
        oDoc = oWord.Documents.Open(path)
 
        Call DoFindReplace("System", "Computer", ActiveDocument.Range)'Problem: Not Declared
        Call DoFindReplace("test", "tempo", ActiveDocument.Range)'Problem: Not Declared
        Call DoFindReplace("car", "bus", ActiveDocument.Range)'Problem: Not Declared
 
        'etc. etc.
 
        oDoc.SaveAs(path)
        oDoc.Close()
        oDoc = Nothing
        oWord.DisplayAlerts = Word.WdAlertLevel.wdAlertsNone
        oWord.Quit()
        oWord = Nothing
    End Sub

Till now the only problem is "ActiveDocument" not declared, but when I play with it, I gort more errors...

Any help appriciated. And yes, this is my first encounter with VB.net or similar. Sorry for bad english.
Zeljko