Microsoft Office 2007 will be released to corporate customers this month and to consumers in January 2007.

Microsoft Office 2007 files have a different file format and file extensions which means documents created with Office 2007 applications will not open with Office 2003, XP, 2000 or Office 97.

So if you're not planning to upgrade to the next version of Office, you will have to download some converters in order to convert Office 2007 files to a format readable by your version of Office.

The Microsoft Office Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats will let you open Office 2007 documents in Microsoft Office 2000, Office XP, or Office 2003. So you can open a .docx file with Word 2003 or .pptx with PowerPoint 2003. It also allows you to create 2007 versions of Word, Excel, or PowerPoint files in your older Office version by opening a blank file and using the Save As command to save it as an Office 2007 file. You can download the Office Compatibility Pack here.

Microsoft will also make available Word 2007 viewer and Excel 2007 viewer shortly after they ship Office 2007, in order to enable users who do not have the respective Office program to open and look at the Office 2007 files.

Microsoft has already made avilable the Visio 2007 Viewer and PowerPoint Viewer 2007.

Visio 2007 Viewer allows to view drawings and diagrams created with Visio 5.0, 2000, 2002, 2003, or 2007. The Visio 2007 Viewer is implemented as an ActiveX control that loads and renders Visio drawings inside Microsoft Internet Explorer version 5.0 or later Web browser.

PowerPoint Viewer 2007 allows to view and print presentations created in PowerPoint 97 and later versions. Supports password-protected PPT files but not macros.

Microsoft has also made available some add-ons for Microsoft Office 2007 and Office 2003.

Microsoft Visual Studio 2005 Tools for Office 2007 is an add-on to Microsoft Visual Studio 2005 that enables you to build application-level add-ins for six applications in the 2007 Microsoft Office system and five in Microsoft Office 2003. Use managed code to customize task panes and the Ribbon in the 2007 Microsoft Office system applications. Also supports InfoPath 2007.

Use Microsoft Office Word 2007 Redaction Add-in (Beta) to hide text within Microsoft Office Word 2007 documents. You can mark text to redact and then create a new, redacted version of the document in which the marked text is replaced with a black bar that cannot be converted back to text.

Office File Converter Pack provides file converters and image filters for Microsoft Office programs, from Microsoft Office 97 to Microsoft Office 2003.

Office 2007 Add-ins Save As PDF and Save as XPS are free add-ons for Office 2007 to export documents from eight Microsoft Office 2007 programs including Word 2007 documents and Excel 2007 Spreadsheets to PDF and XPS file formats without requiring Acrobat Writer. It also allows you to send files as e-mail attachments in the PDF format in a subset of these programs. You can download both the PDF and XPS plugins in one installer here.