Don't buy shitty "gaming headsets"
Sennheiser HD555 $85-100 +
Zalman mic $10 and you'll never go back.
If you scroll down the HD555 page you'll see they are frequently bought together. Then you can mod your HD555's (literally take ear cups off, and remove a small piece of foam in each ear) and they will be HD595's.
"Headsets" with mic's attached are almost always shitty and overpriced. They dumb down on the headphone quality, toss a shitty 5-10$ mic on them if that, then charge you a premium cause they are connected. If you really must get a "headset" which is a waste, then get a sennheiser one. They have a couple of decent options. Also, the quality of your voice through that 10$ zalman clip on mic is quite good. I know tons of people in cod/wow that use this same exact setup, and the clarity is amazing. Plus, you probably won't get better audio until you pass the $200 plateau. Best headphones for less than 100$, best gaming setup for less than $100, and probably the best below $200.
edit: the hd555's are fucking $85 right now which is the cheapest I've EVER seen them. I've bought a few pairs for 90-95.
edit2: razers are shit. I bought one of their headsets for my sister trying to save money off of ebay, and swapped it for a brand new one in bestbuy. The earpieces wore out after a couple months and started to feel like straight plastic cutting your ears, and the audio jack failed every month and needed to be plugged into a different port. Razer is one of the worst brands you could be looking at - they need to stick to mice/keyboards/mousepads. Also a steelseries headset I owned failed miserably after 3 months, waste of like 70$.
edit3: this question is asked twice a month, should sticky it someday or add it to one of the compendium threads.
edit4: if you must get a "headset" then I would suggest
http://www.amazon.com/Sennheiser-HD-.../ref=pd_cp_e_3