Microsoft Office 2007 has a completely new interface which is designed to make it easier to find the functions you need. Whilst this may be the case for new users, old users may find it disconcerting at first to get to grip with the new menu system.
If you are looking for a particular function in Office 2007 and you cannot find it, then the following interactive guides from Microsoft allow you to find the function in Office 2003 and the guide will then tell you exactly where this function is in Office 2007.
Interactive: Access 2003 to Access 2007 command reference guide [Online] [Download] Interactive: Excel 2003 to Excel 2007 command reference guide [Online] [Download] Interactive: Outlook 2003 to Outlook 2007 command reference guide [Online] [Download] Interactive: PowerPoint 2003 to PowerPoint 2007 command reference guide [Online] [Download] Interactive: Word 2003 to Word 2007 command reference guide [Online] [Download]
Moving from Office 2003 to Office 2007
These PDF guides from the University of Liverpool are a really good printable introduction to Office 2007 for those people moving from Office 2003 (or earlier).
Once you have got to grips with the basics you might want to find out more about a particular Office 2007 program. The Florida Gulf Coast University has produced these very helpful web pages showing you how to do pretty much anything you need to.