You might have received files in .docx format that your version of MS Word did not know how to handle. The reason for this is that Microsoft uses a different file format for Word 2007. Users of the new version of Word can save documents in the familiar .doc format, but they have to remember to do so, as the default format is now .docx.

So what can you do if you only have Word 2003 or Word 2002? You can download a compatibility program here that covers Word, Excel and PowerPoint. This is not a perfect solution, as Microsoft points out that some elements in Word documents will be changed by using it:

Although you can open Office Word 2007 files in previous versions of Word, you may not be able to change some items that were created by using the new or enhanced features in Office Word 2007. For example, equations will become images that cannot be changed.

In the long run, we will end up using Office 2007, but if you are not quite ready to make the jump and usually deal with simply formated documents, this compatibility program might bridge that gap for the time being.