This chapter examines the role of operating systems within a multi-vendor data center, and how software and personnel are intertwined within an organization. In an ideal world, training wouldn’t be attached to a tangible cost. Since expenditures do matter, however, and OS licensing costs are a growing concern for data center managers, organizations need to ensure that quality takes precedence over quantity. The chapter focuses on cross-training Windows and Linux, which helps to limit spending and ensure that migration off legacy proprietary OSes occurs without a hitch. Since a majority of the apps live on these platforms, and the software receives updates, a more thorough approach will be beneficial to the organization.