Embodiments of the invention relate to a centralized managing system and method for creating, deploying, administering, and managing a plurality of separate and distinct virtual computer networks on a virtualization platform for offering cloud computing services (SaaS). Embodiments of the invention relate to a computer system for a centralized management of separate and distinct virtual computer networks, which has a security grid which has at least one grid processor and a memory device that stores a managing application. The managing application has a virtualization platform, a grid access layer, a virtual computer network template system, a plurality of resource distribution tools and a plurality of monitoring and metering tools. The grid processor is adapted by the managing application so that it can create, deploy, administer, and manage the plurality of separate and distinct computer networks.