Multimedia applications are emerging in education, information dissemination, entertainment, as well as many other applications. The stringent requirements of such applications make design of cost-effective and scalable systems difficult, and therefore efficient adaptive and dynamic resource management techniques can be of great help in improving resource utilization and consequently improving performance and scalability of such systems. In this paper, we focus on threshold-based policies, for dynamic resource management, and specifically, in the context of continuous media (CM) servers. Furthermore, we propose a mathematical model of user behavior and show, through a performance study, that not only does the use of this model in conjunction with dynamic resource management policies improves the system's performance but that it also facilitates significantly reduced sensitivity to changes in: (a) system architecture, (b) workload characteristics, (c) skewness of data access patterns, (d) frequency of changes in data access patterns, and (e) choice of threshold values. We believe that not only is this a desirable property for a CM server, in general, but that furthermore, it suggests the usefulness of these techniques across a wide range of continuous media applications. Also cross-referenced as UMIACS-TR-98-61