In this paper we show how Queuing Petri Net (QPN) models can be exploited for performance analysis of distributed e-business systems. We study a real-world application, and demonstrate the benefits, in terms of modelling power and expressiveness, that QPN models provide over conventional modelling paradigms such as Queuing Networks and Petri Nets. As shown, QPNs facilitate the integration of both hardware and software aspects of system behavior in the same model. In addition to hardware contention and scheduling strategies, using QPNs one can easily model simultaneous resource possession, synchronization, blocking and contention for software resources. By validating the models presented through measurements, we show that they are not just powerful as a specification mechanism, but are also very powerful as a performance analysis and prediction tool. However, currently available tools and techniques for QPN analysis are limited. Improved solution methods, which enable larger models to be analyzed, need to be developed. By demonstrating the power of QPNs as a modelling paradigm in realistic scenarios, we hope to motivate further research in this area.