The Kingston X (they have a new model inbound soon too) is by far the most recommended headset out there in the gaming world, especially for the $. I have one hooked up to one of our other gaming PCs and it's been great for 70$ CDN, about 50$ US on sale.
I tell anyone the best bang/$ if you want a really, really good pair of phones is the Sony MDRs in this thread - Challenge has the same model too I believe, and they are truly a Pro quality set of phones and are ridiculously low priced for what you get, I got mine for 100$ USD or so IIRC. You do need a mic though, so either a modmic or a stand alone mic, which is usually a bit better than typical gaming "headset" mics anyway, just much more $. A good DAC is great too, you don't need to spend a pile of $ on the X7 either, there are tons of other options out there which work great, like a Felio E10k or some such.