Service-oriented Architecture (SOA) is becoming the prevalent architectural style for the creation of agile and flexible enterprise IT infrastructures. Services, as the key elements of Service-oriented Computing (SOC), can be composed in very efficient way to support flexible business processes and to adapt application systems quickly to new business requirements. Virtualization technologies offer cost-effective and rapid resource scalability as well as greater flexibility in providing hardware resources to service demands. However, also service-oriented applications need to be tested, monitored and maintained; thus the management aspect of Service-oriented infrastructures is often neglected. We propose a Service Management System that enhances the management of infrastructures for SOC and describes a first step towards the self-management of services in infrastructures with virtualized hardware resources. This paper provides a core set of components and required management functions that must be considered in providing a Service Management System for SOC.