Convert XLS to tab delimited.

Use ADO and the Jet OLEDB provider, which can read the contents of excel files without actually opening Excel.

Example:

'*******************************

Public  
    Sub ConvertXLSToTab( 
    ByVal xlsFileName  
    As  
    String,  
    ByVal tabTextOutputFile  
    As  
    String)  
    
         
    Dim connectionString  
    As  
    String =  
    "
Provider=Microsoft.ACE.OLEDB.12.0;Data Source='
" & xlsFileName &  
    "
';Extended Properties='Excel 12.0;HDR=YES';
"

         
    Dim strSQL  
    As  
    String =  
    "
SELECT * FROM [Sheet1$]
"

         
    Dim excelConnection  
    As OleDb.OleDbConnection =  
    New OleDb.OleDbConnection(connectionString) 
    
        excelConnection.Open() 
    
         
    Dim dbCommand  
    As OleDbCommand =  
    New OleDbCommand(strSQL, excelConnection) 
    
         
    Dim dataAdapter  
    As OleDbDataAdapter =  
    New OleDbDataAdapter(dbCommand) 
    
         
    Dim ds  
    As  
    New DataSet 
    
        dataAdapter.Fill(ds,  
    "
dTable
") 
    
         
    '
DataGridView1.DataSource = ds.Tables("dTable").DefaultView

         
    Dim strLine  
    As  
    String

         
    Dim objStreamWriter  
    As StreamWriter 
    
        objStreamWriter = File.CreateText(tabTextOutputFile) 
    
         
    For  
    Each row  
    As DataRow  
    In ds.Tables( 
    "
dTable
").Rows 
    
             
    Dim column  
    As DataColumn 
    
            strLine =  
    ""

             
    For  
    Each column  
    In ds.Tables( 
    "
dTable
").Columns 
    
                 
    If (strLine <>  
    "")  
    Then strLine = strLine & vbTab 
    
                strLine = strLine & row(column).ToString() 
    
             
    Next column 
    
            objStreamWriter.WriteLine(strLine) 
    
         
    Next row 
    
        excelConnection.Close() 
    
        objStreamWriter.Close() 
    
     
    End Sub