The acquisition of complex software intensive systems is fraught with significant risks and often incurs schedule delays, cost overruns and reduced functionality when the product is finally delivered. This paper presents a model to assess the effectiveness of software intensive acquisitions, founded on the premise that the solution depends on a series of transformations that transform input products in one domain into output products in another domain. Transformations are performed by people, and require knowledge and skills pertinent to both input and output domains. Ideally, products should be transformed without distortions resulting into the desirable solution. In reality, distortions occur because people are limited by their own knowledge, skills, cognition, emotions and are moved by personal and corporate goals and bounded by their roles in the social organisation. The proposed model represents the products of a domain as vectors in a vector space; and tasks as transformations that change products from one domain into another. The Analytic Hierarchy Process (AHP) is used to determine the input values for the model, to quantify a physical situation so that it can be manipulated by vector mathematics. Transformations require a nominal level of knowledge, skills and effort to be executed without distortions, which occur when the person executing the transformation possesses less than the required knowledge and skills, or has those skills subverted by other factors, reducing the effectiveness of the acquisition. The effect of 'Chinese Whispers' is easily demonstrated with the model and is an analogy of the type of distortion that can occur. A case study based on the acquisition of an integrated tactical and avionics system for the Super Seasprite SH-2G(A) Helicopter is presented to demonstrate how the model proposed in this paper can be applied to a defence software intensive acquisition. The paper concludes by showing how the proposed task model provides the basis for a more comprehensive model that can be applied to understand, explore and design complex acquisitions.