This paper presents the design of a HTTP Adaptive Streaming WebTV Client, featuring smooth media Rate Adaptation, context Personalization, fast program channel switching and Terminal/Network Portability capabilities. The QoS-Awareness during streaming is achieved dynamically by a regulating technique that takes into account network conditions, user's device capabilities and the context of viewing. By dynamically optimizing the video quality experienced by the user, the solution provides an excellent streaming application and protocol for heterogeneous network environments.