Developing an IT-strategy of cloud deployment is a complex issue since even the stage of its formation necessitates revealing what applications will be the best possible to meet the requirements of a company business-strategy, evaluate reliability and safety of cloud providers and analyze staff satisfaction. The present paper suggests a system approach to evaluate the effectiveness and risks resulted from the integration of cloud-based services in machine-building enterprise. This approach makes it possible to estimate a set of enterprise IT applications and choose the applications to be migrated to the cloud with regard to specific business requirements, technological strategy and willingness to risk. A system of criteria as well as integrated model to assess cloud deployment effectiveness is offered.