John Walkenbach is a leading authority on spreadsheet software and is principal of JWalk and Associates Inc., a small San Diego–based consulting firm that specializes in spreadsheet application development. He is the author of approximately three dozen spreadsheet books and has written hundreds of articles and reviews for a variety of publications, including PC World, InfoWorld, Windows magazine, and PC/Computing. John graduated from the University of Missouri and earned a master’s and a PhD from the University of Montana. Visit his Web site at www.j-walk.com.

Colin Banfield has been working in the telecommunications field for more than twenty-five years and has been using spreadsheet programs for more than two decades. Colin’s largest Excel project to date is a comprehensive tool that is designed for telephone central office equipment configuration, pricing, and manufacturing and used by sales, engineering, and manufacturing personnel. In between his telecom consulting duties, Colin works with organizations to extract information from corporate databases for business intelligence reporting in Excel. In his spare time, Colin writes and reviews books for Wiley and enjoys photography, astronomy, and expanding his musical repertoire. Colin holds a BSc (Honors) in Electrical Engineering from the University of the West Indies and has received extensive training in many advanced technologies.