In order to download Excel files (files with the extension .xls), you will need to configure your Web browser to recognize Excel files and save them to disk, rather than trying to display them in the browser window. To configure your browser, edit your list of helper applications. (In Netscape, open the menus Edit.. Preferences.. Applications.) Set the type as application/x-excel, the extension (suffix) as xls, and the action as "save to disk".
Numerical integration
spreadsheet