Spreadsheet::ParseExcel only handles the Excel binary files format called Biff that is used in Excel versions prior to 2007. Excel 2007 has a new file format that is comprised of zipped XML files. This is not handled by Spreadsheet::WriteExcel.

If you unzip the 2007 xls file (change the extension to .zip if necessary) you can probably parse the information out of the embedded XML files using one of the Perl XML parsers.