There is such thing as "gaming" headphones, that's the name for overpriced, shoddily built, crap sound peices of crap.
I'll never look back since going the hi-fi route of amp/headphones/stereo speakers.
It's not top notch stuff but so much better than the "gaming" stuff I had before, including at the time what I thought were pretty good Medusa's (which I now think are utterly atrocious)
To start off go for something like a desktop microphone, or a clip on one.
Then grab yourself some good quality headphones, but it's a matter of personal preference this. I use some AKG 240s Studios for most of my PC use, but also have some Beyeydynamic DTX900's and some Grado SR80 and 60's which are more usually used with music.
Then later on look at a stereo amp and some speakers if you don't want to use headphones.
(and yes I now that Grado's fall to bits before anyone says it
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