Users who use an earlier version of Excel can also download the Microsoft Office Compatibility Pack for 2007 Office Word, Excel and PowerPoint File Formats to install updates and converters for the earlier version of Excel. This allows them to open, edit, and save an Excel 2007 workbook in the earlier version of Excel, without having to save it to that version's file format first or without having to upgrade the earlier version of Excel to Excel 2007.

Users of the Microsoft Office XP and 2003 programs Word, Excel, or PowerPoint—please install all High-Priority updates from Microsoft Update before downloading the Compatibility Pack.

By installing the Compatibility Pack in addition to Microsoft Office 2000, Office XP, or Office 2003, you will be able to open, edit, and save files using the file formats new to Word, Excel, and PowerPoint 2007. The Compatibility Pack can also be used in conjunction with the Microsoft Office Word Viewer 2003, Excel Viewer 2003, and PowerPoint Viewer 2003 to view files saved in these new formats.

http://www.microsoft.com/downloads/details.aspx?FamilyId=941B3470-3AE9-4AEE-8F43-C6BB74CD1466&displaylang=en

thanx!!

Why not we go with OpenOffice 3.0? It supports all versions of MSoffice files and it's free. We can save a file in different versions of microsoft office file format.

i prefer microsoft solely because of its relaibilty