Software infrastructures that support metacomputing are evolving from traditional monolithic, platform-specific systems to component and service-based frameworks. In this paper we demonstrate that contrary to popular belief, such modular software systems are capable of delivering good to excellent performance, support legacy as well as new application programming paradigms, and deliver enhanced functionality. The Harness system, a software backplane enabling reconfigurable distributed concurrent computing is used to emulate the PVM programming environment. Numerical kernel benchmarks show that application performance results using the emulator and native versions are within a few percent of each other. Coupled with the ability to leverage pre-existing and specialized modules, our experiences suggest that service-oriented computational grids may be constructed rapidly and effectively via such component-based architectural frameworks that deliver full functionality without compromising efficiency.