OCModShop posted a review on the Plantronics Gamecom 777 7.1 Surround Gaming Headset
The sound from the Gamecom 777 7.1 is very good, with crisp highs and good bass, and has a good energy to it. In stereo mode, the headphones sound absolutely great for music listening. Throwing the switch on the included USB soundcard adapter is when things start to go awry, as positional sound is not very convincing most of the time. Everything sounds more spatial, but just not very directional. Since all surround is interpolated from a 2-channel stereoPlantronics Gamecom 777 7.1 Surround Headset Review
source, then the effectiveness of the surround field can be very subjective.
One advantage to these headphones is that they will work on just about any analog device, from iPods to CD players to PCs. The included USB-based surround sound card just isn't effective beyond making things sounding more ethereal. This headset retails for $99, but fortunately can be found online for as little as $59. At that price, it's definitely better than others in that price range.