RE: Excel Interop

           Application ExcelApp = new Application();

           Workbook ExcelWorkBook = ExcelApp.Workbooks.Add(1);

           Worksheet ExcelWorkSheet = (Worksheet)ExcelWorkBook.Sheets[1];

           ExcelWorkSheet.Cells[1, 1] = "test";

           ExcelWorkBook.SaveAs(@"C:\temp\test1.xlsx");

           ExcelWorkBook.Close();

           ExcelApp.Quit();

Here is the C# code.