Word 2003 did not include forward compatibility with Word 2007, so that would be proper.
However the good news is that Microsoft has a Compatibility Pack for Office 2003 users to enable them to open, edit, and save documents in the new Office 2007 formats.
It would save the expense of purchasing the full Office 2007 product.
I hope that helps.
> I am not able to open word documents ( office 2007) in a computer that has office 2003 installed?
> Can i install both office 2003 and 2007 in a single PC?