Well, you might be aware now that - MicrosoftOffice 2007introduced a new file format called the MicrosoftOpen Office XML Format (.xlsx). But unfortunately this format is not compatible with older versions of Microsoft Excel(like Office Excel 2003 / Excel XP) or with alternative operating systemslike Linux or Mac OS X. Nor is it compatible with other word processing applications like OpenOffice, Lotus 123, or NeoOffice.Below are some easy solutions on how you can still open your xlsx files in other systems and also easily convert it to previous versions of Excel.
- Install the latest version of Microsoft Office Compatibility Pack and it'll be able to detect the .xlsx file format and help you convert it to .xls file format.
- Use the Online Solution found here to convert your .xlsx to be used in other formats too.