Many enterprises have a heavily mixed environment including mainframe, AIX, Linux and Windows. Virtualization of Intel based servers and desktops are also a well-accepted strategy adopted by large IT organizations. The cost benefits are significant, but for the capacity planner, the challenges are evolving almost as fast as new devices are appearing. This presentation will delve into some of the basic challenges of managing a large organization with mixed platforms and will discuss the environment from a performance and capacity perspective. It will introduce the benefits that can be derived by using ASG PERFMAN in these deployments. Finally we will introduce a capacity planning methodology that can take much of the guess work out of planning for growth.