This research work intends to analyze the pros and cons of private clouds and public clouds for the IT firms, who can utilize this pool of resources to economize their computing resources and data storage resources. The details of this analysis would help the IT firms to upgrade their existing data centers to virtual private clouds so that they can exploit the resources of the public clouds through a pay per use service level agreement. This sort of analysis can be best presented by a typical case study methodology. The case study methodology enables an in-depth examination of one or few chosen IT company(s) who have implemented the virtualization techniques. This research has chosen the IT firms like Cisco, EMC2 and VMware who have been the forerunners in the virtualization of datacenters. Based on the learnings of the case study, this research aims to support the hypothesis that the private clouds are a prerequisite for virtual clouds. This chapter gives a detailed understanding of the concepts related to cloud computing like cloud services, cloud platforms, key service providers of clouds and key actors, the architecture of cloud computing facility, the privacy and security aspects in cloud computing. Apart from the technical aspects, this chapter also discusses the change management strategies that need to be followed in migrating from legacy datacenters to virtual private clouds. As the maintenance of data center facilities is more crucial, IT managers would be more interested to use the data center utilities if they are provided on-demand basis. The best option for such a facility happens to be the cloud computing environment. A definition for Cloud computing from Macmillan dictionary is a type of computing in which computing resources are shared via the Internet, rather than the use of local servers or personal computing devices (http://www.macmillandictionary.com/buzzword/entries/cloud-computing.html).