Open 2007 ms office file in 2003 ms office

Microsoft office 2003 and 2007 are different versions.we can open 2003 file in
2007,but we can open 2007 file in 2003 office.Because it is new version.2003
office file formats are,word save as .doc, powerpoint save as .ppt ans Excel
save as  .xls. 2007 office formats are different,word save as .docx, powerpoint 
save as .pptx and Excel save as .xlsx.So, 2003 cant identify 2007 format.
But there is a way given from Microsoft. We can follow it.

You have to download this pack and install it.

http://www.microsoft.com/downloads/details.aspx?FamilyId=941b3470-3ae9-4aee-8f43-
c6bb74cd1466&displaylang=en

After you installed this pack ,you can open 2007 office file in 2003 office.