I know many people continue to struggle with finding commands on the new Excel 2007 Ribbon. There are also numerous add-ins available that will provide a 2003 style toolbar on the 2007 Ribbon.
If this is you, and you need the reassurance of having the 2003 toolbar available while you are getting familiar with the Excel 2007 Ribbon, then you might want to try the Ribbon Customizer by Patrick Schmid. Patrick has made it available in two versions, a free Starter Edition and a chargable Professional Edition which includes enhanced functionality.
If all you are wanting is to access the Excel 2003 toolbar from within Excel 2007, then the Starter Edition will facilitate using Excel 2007 while still providing the familiar Excel 2003 “classic” toolbar. This gives you the best of both worlds while you get used to the new Excel 2007 Ribbon interface.
UPDATE: An alternative add-in is also available from Shah Shailesh [here] with versions for Excel 2003, Word 2003 and Power Point 2003.