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How to Open xlsb File?
http://www.vistaarticles.com/articles/420/1/How-to-Open-xlsb-File%3F
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Published on 05/20/2007
 
Non XML binary workbook File.

How to Open xlsb File?

Format used in Microsoft Excel 2007. To use earlier versions of Microsoft Excel to open files from Excel 2007 download Compatibility Pack.

Download Free Compatibility Pack from Microsoft:
http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=941b3470-3ae9-4aee-8f43-c6bb74cd1466