Intel Labs has continued development of the Embedded Transport Acceleration (ETA) software prototype that uses one of the Intel? Xeon™ processors in a multi-processor server as a packet processing engine (PPE) that is closely tied to the server's core CPU and memory complex. We have further developed the prototype to provide support for user-level, asynchronous interface for sockets. The Direct User Socket Interface (DUSI) allows user-level applications to interface directly to the PPE using familiar socket commands and semantics. The prototype runs in an asymmetric multiprocessing mode, in that the PPE does not run as a general computing resource for the host operating system. We describe the prototype software architecture, the DUSI application interface, and detail our measurement and analysis of some micro-benchmarks. In particular, we measure throughput for transactions and end-to-end latency as the key metrics for the analysis.