How to Open XLSM, XLSX, XLSB, XLTX, XLTM and XLAM Files in Excel 2003 and 2002

1. Go to the Microsoft Download Center (link in Resources) and select 'Microsoft Office Compatibility Pack for Word, Excel, and PowerPoint File Formats,' located under the 'Popular downloads' heading. Click the 'Download' button on the right side of the ensuing page.
2. Click 'Run' if you are using Internet Explorer; click 'Open' if you are using Google Chrome; click 'Save File,' then double-click the downloaded file if you are using Mozilla Firefox.
3. Click 'Yes' if you are prompted by the User Account Control window. Read the license terms and select the 'Click Here to Accept the Microsoft Software License Terms' check box if you agree to the terms and wish to continue with the installation. Click the 'Continue' button.
4. Close Excel and any other Microsoft Office programs that are currently running after installation is complete, then open Excel to enable the Compatibility Pack. You can now open, edit and save all Excel 2007 or 2010 file formats in your edition of Excel.