Hope you enjoy them, I opted not to go the "true" 5.1 headphone route, however I am also extrmely pleased with what I ended up with and if any of you have about $200 and want a nice solution.
I got a stereo pair of Sennheiser HD555 headphones (I think sennheiser also makes a version with a built in mic, the pc250 or pc350 I think).
Plus an Asus Xonar D1 soundcard that does Dolby Headphone processing. I gotta say, I dont know how the surround effects are in the 5.1 headphones, but I think i ended up with the best of both worlds, great quality stereo headphones and awesome surround using dolby headphone. (I know its simulated surround, but I can tell you that it does actually work, and works well).
Either way, let us know what you think about your new headphones when you get them