Hello
I personally bought the Medusa 5.1 USB headsets just because they were £30 cheaper than the other gaming headphones out there. Started off well, but the microphone is found lacking when it comes to teamspeak/ventrillio. This is quite annoying when your teammates constantly say they cant hear you
Now, these (with the USB soundcard) include virtual 5.1 surround sound, which is quite good, and adequate for gaming.
Now, there headsets such as the icemat siberias have decreased in price rapidly. They are only £40 on OcUK, and they offer superior sound in games and music. Their only downpoint is thier build quality, with many reported complaints about them breaking easily. However, if you dont plan on going to lan parties i doubt these headsets will take much damage. Their mic is a clip on device, like the ones they use in TV interviews, and is also quite weak.
There is an option of buying the optional Icemat Sound card, £19 form OcUK as well. The main selling point of this card is that it offers virtual 7.1 surround sound if the game supports it. This offers that extra edge for the gamer.
As you have a 7.1 soundcard, i would just purchase the icemats without the soundcard. If you plan to travel with the headsets and want the same quality sound no matter what pc you use, buy the USB soundcard as well.
--Alternative Choice--
Now, if you are feeling like breaking the £50 barrier, the best headset is avaliable for purchase, the Steelsound 5h. These have had brliiant reviews all over the internet, and thier microphone is excellent, build quality excellent, sound quality excellent, but thier price expensive. These also have thier own optional soundcard, but i have yet to see a UK retailer selling the headsets with thier USB soundcard...
If you dont feel like spending £50, the icemats offer the same sound quality for a lesser price.