Peer-to-peer networks continue to gain popularity, but the problem of locating suitable peers still remains formidable. The lack of globally accepted standards and protocols is another problem that further creates the issue of a lack of global connectivity. This paper presents a hybrid P2P infrastructure, called PSI, which uses Web Services as registries to locate peers. We also formally define the set of basic operations that are performed during peer search to determine optimized connectivity. Heuristics for locating peers are based on preference values computed using historical data. The PSI model is compared to other models with respect to suitability for integrating a set of distributed and heterogeneous peers. The mechanism for locating files depends only on discovering and using Web Services. The greatest advantage of this is the possibility of global connectivity. The understanding gained by analysis and preliminary implementation confirms that the model is highly scalable.