Microsoft Office 2007
Students and instructors may encounter difficulty opening files that were created in the latest version of Microsoft Office (2007).
The easiest way to insure that your students or instructor can open your files is to make sure and Save as... Office 2003 file. If you recieve an Office 2007 file that you can't open, you can download a plugin that will allow you to open the file.
Office Plugin
Microsoft offers a plugin that addresses this issue when using a previous version of office to open new files.
According to Microsoft:
"By installing the Compatibility Pack in addition to Microsoft Office 2000, Office XP, or Office 2003, you will be able open, edit, and save files using the file formats new to Word, Excel, and PowerPoint 2007. The Compatibility Pack can also be used in conjunction with the Microsoft Office Word Viewer 2003, Excel Viewer 2003, and PowerPoint Viewer 2003 to view files saved in these new formats."
Windows users may download the plugin here: DocX converter (27MB)
Mac users can get the plugin here: DocX converter (21.1 MB)