Following is the code that I use to open an Excel 2000 file. Hope this helps you.
GC
############### CODE FOLLOWS #############
Sub Main
' Get the main system object
Dim Sessions As Object
Dim System As Object
Set System = CreateObject("EXTRA.System"

' Gets the system object
If (System is Nothing) Then
Msgbox "Could not create the EXTRA System object. Stopping macro playback."
STOP
End If
Set Sessions = System.Sessions
If (Sessions is Nothing) Then
Msgbox "Could not create the Sessions collection object. Stopping macro playback."
STOP
End If
' Set the default wait timeout value
g_HostSettleTime = 300 ' milliseconds
OldSystemTimeout& = System.TimeoutValue
If (g_HostSettleTime > OldSystemTimeout) Then
System.TimeoutValue = g_HostSettleTime
End If
' Get the necessary Session Object
Dim Sess0 As Object
Set Sess0 = System.ActiveSession
If (Sess0 is Nothing) Then
Msgbox "Could not create the Session object. Stopping macro playback."
STOP
End If
If Not Sess0.Visible Then Sess0.Visible = TRUE
Sess0.Screen.WaitHostQuiet(g_HostSettleTime)
' Declare variables to contain the OLE objects
Dim objExcel As Object
Dim objWorkBook As Object
Dim objChart As Object
On Error Resume Next
' Attempt to get a reference to an open instance of Excel 97/2000
Set objExcel = GetObject(, "Excel.Application"

If objExcel Is Nothing Then
'If GetObject failed, open a new instance of Excel 97/2000
Set objExcel = CreateObject("Excel.Application"

If objExcel Is Nothing Then
MsgBox ("Could not open Excel 97/2000."

Exit Sub
End If
End If
' Make Excel visible on the screen
objExcel.Visible = True
' Create a new Workbook
' Set objWorkBook = objExcel.Workbooks.Add
'************************************ change yourfile.xls to the file you wish to open.***************
'************************************ change yourfile.xls to the file you wish to open.***************
'************************************ change yourfile.xls to the file you wish to open.***************
'************************************ change yourfile.xls to the file you wish to open.***************
' Open a Workbook
Set objWorkBook = objExcel.Workbooks.Open("yourfile.xls"
'************************************ change yourfile.xls to the file you wish to open.***************
'************************************ change yourfile.xls to the file you wish to open.***************
'************************************ change yourfile.xls to the file you wish to open.***************
'************************************ change yourfile.xls to the file you wish to open.***************
If objWorkBook Is Nothing Then
MsgBox ("Could not open a new Excel workbook."

objExcel.Quit
Exit Sub
End If
' Since the Quit method of objExcel has not been called,
' Excel will remain open after this Sub ends.
' To close out Excel, unremark the following 4 lines of code.
'objWorkBook.Close
'objExcel.Quit
'set objWorkBook = Nothing
'set objExcel = Nothing
End Sub