How can somebody with Excel 2003 read Excel 2007
 

I have an Excel 2007 and would like so send an email to a freind with excel
2003 . How can he read my excel workbook?

I think your only option is in your 2007 version 'save as' "Excel 97-2003"
This will convert to the previous format however if you have used any functions specfic to 2007 these will be lost

How can somebody with Excel 2003 read Excel 2007
 

Either the Excel 2007 user needs to save the file in an earlier format (using
the Save As dialogue), or the Excel 2003 user needs to download the file
converter from the Microsoft website.