I have never tried the medusa so can't comment on that one.
I am however using the Zalman 5.1 headphones w/mic and have had it for about 6 months. I can say it has improved my gaming due to the sound placement. Its much harder to blindside me or sneak up on me now whether single-player or multi. Music is imo a little more full than with my old plantronics or logitech headsets and just sounds better to me.
I have seen a few people say its not for them or the cords are too thin etc. but I love mine and for the price I think they're hard to beat for 5.1 sound in a headphone. They don't compare to ones costing 100s of dollars but I can't see dropping that much on headphones anyway since I mainly use mine for FPSs or when the family goes to bed
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EDIT: Forgot to mention, yes this headset will work with your soundcard and give you fully functional 5.1 sound. Some other posters mentioned that some of the other brands do not so wanted to clarify that point for the Zalmans.