Whether for an individual or an organisation, buying a computer is a serious matter; it represents a sizeable financial outlay, even with consistently falling prices, and decisions are complicated by the current and foreseeable state of the computer market-place, particularly the following factors: (i) there are more types of computer, more alternative models from different suppliers, and a greater range of performance between the largest and smallest than in any other area of technology; (ii) the high rate of technological progress means that most models are lucky if they survive for two years before their manufacturer brings out a better machine for the same price or a cheaper machine with the same performance; as a result many models and some suppliers will not survive; (iii) in an expanding marketplace, many newly-arrived outlets have little experience of the business and even less credibility; (iv) the industry has a tradition of aggressive marketing and vigorous competition. As a result, caveat emptor applies very strongly, as getting it wrong and having to start again can be very expensive.