I've heard these are pretty good, gonna pick up a pair myself - http://www.amazon.co.uk/Plantronics...1_1?s=computers&ie=UTF8&qid=1347635837&sr=1-1
I have the corsair hs1a and I quite like it. Its comfortable, if a bit heavy, and produces decent enough sound. Also that leaves some of the budget left over for something like the asus xonar DG.
Nothing beats the JVC RX700 (with foam mod) and a clip on mic. Avoid USB headphones. Also don't get the asus xonar DG as your motherboard doesn't support PCI. You would have to get the asus xonar DGX, but I would fork out the extra cash and get the asus xonar DX. JVC RX700 http://www.amazon.co.uk/JVC-HA-RX70...1?s=aps&ie=UTF8&qid=1347656063&sr=1-1-catcorr Foam mod http://www.head-fi.org/t/435809/jvc-ha-rx700-mods Clip on mic http://www.amazon.co.uk/Speedlink-I...1?s=electronics&ie=UTF8&qid=1347656119&sr=1-1
They tend to be noticeably worse compared to analogue headphones as you are forced to use whatever in built sound card comes with them. Analogues can be plugged into quality sound cards on the other hand, providing a future upgrade path. I would recommend the RX700s and clip on mic too, awesome budget headphones.
...In hindsight, I shouldn't have linked them, should've kept them to myself. But I guess sharing is caring.
Trust me you don't want a 7.1 surround sound headset. The JVC RX700's I recommended are a lot better.