Managing a large IT implementation is challenging for any company, but the risks increase when the end users are external customers and the price of failure is damage to the bottom line. Careful planning of the design and rollout is thus crucial. No one knows this better than software product companies, such as Microsoft and Oracle, which live or die by how well they introduce products that both meet their customers' needs and keep their cost base competitive. They realize the importance of understanding what customers want, of market research and customer support, and of maximizing value by striking a balance between satisfying buyers and controlling costs.

In these respects, software product companies have much to teach internal IT organizations, whose project-management practices usually fall short when it comes to developing and executing customer-facing systems. Too often the IT organization assumes that someone in marketing or sales has done the up-front market research or that budget-busting modifications to the features of systems are customer driven and absolutely essential. Such faulty assumptions can have serious consequences: whereas internal customers usually have no choice but to adopt a new solution—even a poorly designed one—external customers can go elsewhere. During the recent refinancing...