For gaming, with some movies and music, I prefer the SteelSound 5H headset. I had Sennheiser PC150 but while the sound was clear, it was also a bit flat. It simply lacked punch.
As for 5.1 headsets, the SpeedLink Medusa seems to get good reviews, although I think that 5.1 headphone sound is not much more than marketing, since it won't substitute a true 5.1 speaker system.