It is not uncommon to receive an e-mail attachment from someone that is using a newer version of Microsoft Office than you are. Or perhaps you are using a computer that doesn't have any version of Office installed on it at all. For these cases, Microsoft provides Office Viewers. The are applications that you can install that allow you to open different versions and formats of Office files.
Here is the link to the Microsoft web site with the Viewer applications.
The more common instances of this effect come up with the new Office 2007 versions of files (since a lot of people are still using the 2003 version of Office). The common extensions for Office 2007 are:
Word .docx
Excel .xlsx
Note the x on the end of the extension. If you see these extensions, and don't have Office 2007, you will need to download the appropriate viewer from the link above.
The more common instances of this effect come up with the new Office 2007 versions of files (since a lot of people are still using the 2003 version of Office). The common extensions for Office 2007 are:
Word .docx
Excel .xlsx
Note the x on the end of the extension. If you see these extensions, and don't have Office 2007, you will need to download the appropriate viewer from the link above.