This book tells "what to", "why to" and "when to" use personal computers (PCs) for carrying out scientific computing tasks. There are many books that purport to tell users how to operate particular software packages or to set up and maintain their personal computer hardware. These "how to" volumes have their proper role and utility. Our goal is different: we aim to present ideas about the management decisions involved in using PCs for scientific and technical computing. The audience for this book is any scientist, engineer, statistician, economist, or similar worker who is considering using a personal computer for all or part of his or her technical work. The ideas we present can be used at the individual or group level. Being ideas about the management of resources, they are kept simple to the extent that readers will think "I know that." We stress, however, that it is the day-to-day practice of management ideas that counts; theoretical knowledge is like a smoke alarm without a battery.