Not sure if this will work in Excel 2000 or not. It was tested with Excel 2002(XP).
This example reads an HTML file into a good sized TextBox that has the MultiLine property set to True and the ScrollBars property set to fmScrollBarsVertical.
TextBox1.Text = ""
Set fs = CreateObject("Scripting.FileSystemObject")
Set f = fs.GetFile("C:\test.html")
Set ts = f.OpenAsTextStream(1, 0)
s = ts.readall
TextBox1.Text = s