In addition to Suzanne's response, most of the keystrokes that worked in
Word 2003 continue to work in Word 2007, despite the fact that no menu is in
evidence. Hence, Alt+F A also brings up the Save As dialog. (Since the
Office button essentially is Office 2007's de facto equivalent of the File
menu from earlier versions of Word, Alt+F displays it).
When you click on the Office button, you can right-click on Save As and
choose Add to Quick Access Toolbar to place that tool onto the QAT. You can
also right-click the QAT and choose to show the QAT below the ribbon, which
many find a bit handier and easier to reach than way up at the top of the
Word window.
In fact... you can place a lot of the Word 2003 tools onto the QAT, and with
it displayed below the ribbon, it can be made to resemble the Word 2003
formatting and/or standard toolbars (albeit, just one), as shown here:
http://word2007bible.herbtyson.com/2007/05/02/making-word-2007-a-little-more-familiar/