In most of the 2007 Office programs, the File menu has been replaced with the Microsoft Office Button. Click this button (found in the upper-left corner of the window) to locate commands to open, save, and print your documents. Note that Options are also available at the bottom of this popup.
The Quick Access Toolbar is a customizable toolbar that contains commands that you may want to use frequently. To customize the toolbar, click on the arrow at the end and choose commands to check or uncheck them. If you don't see the command you want, choose 'More Commands..."
You can place the Quick Access Toolbar above or below the ribbon. To change the location of the quick access toolbar, click on the arrow at the end of the toolbar and click Show Below the Ribbon.
The Ribbon is the panel at the top of the document. You can click on each command (tab) to view different ribbons. Note that the ribbon is context sensitive and will change depending on what you're doing.
Each tab is also divided into groups. The groups are logical collections of features designed to perform functions that you will utilize in developing or editing your documents. The most commonly used features are displayed on the Ribbon; to view additional features within each group, click on the tiny arrow in the bottom right corner of each grouping.
When you select text, you will see a handy, miniature, semi-transparent toolbar called the Mini Toolbar. The Mini toolbar helps you work with fonts, font styles, font sizing, alignment, text color, indent levels, and bullet features. 
In Office 2007 applications, a new file format called XML is used. Why? This new format allows for increased security , reduced chance of file corruption, reduced file sizes, and new features.
Word 2007 documents will have the extension of .docx; Excel 2007 documents will save with .xlsx; PowerPoint 2007 will save with .pptx, and so on to denote the new XML format..
When you open a file that was created in an older version of Office, you'll notice the file name appears with "Compatibility Mode" next to it.
You can open a file that was created in Office 95 through 2003, edit the document, and continue to save with the same old extensions. However, you will not have access to some of the newest features until you save in the new format.
When you save a file created in a previous version, the default in the Save As dialog box is to save as a previous version. You can also elect to save the file as a 2007 version.When you save a file as a previous version, a Compatibility Checker will let you know of any 2007 features that may be disabled or matched as closely as possible.
