If you cannot open an Excel file and see Excel cannot open the file because the file format or extension is not valid error, see this post.

If you think that OpenOffice.org is just an open source alternative to Microsoft Office, think again. Find out how it can serve as a component in your Web-based spreadsheet applications.

Microsoft Excel has several features designed to help you recover unsaved versions of files and prevent data loss.

Microsoft Word can accommodate a surprising number of file formats, and even take in Excel and PowerPoint data, though it might look funny. Here's how.