This paper explores microarchitecture models for a simultaneous multithreaded processor with multimedia enhancements. We enhance a wide-issue superscalar processor by the simultaneous multithreading technique, by multimedia units, and by an additional on-chip RAM storage. Our workload is a multithreaded MPEG-2 video decompression algorithm that extensively uses multimedia units. Our simulation results suggest that a 2- or 4threaded 4-issue processor with a small on-chip RAM accessed by a local load/store unit will be superior to a wide-issue (single-threaded) superscalar processor.