I'd put a link to a good article here <missing link> but I need permission to add an external link to Life Hacker's post on audio quality choices for headsets and stand alone microphones.
I am looking at a better quality entry level headphone setup. I decide to go with Audio Technica's ATH-M40x, though I really wanted the Sennheiser HD-595's. But I kept losing my bids on them and finally said to heck with it. The Audio Technica look to be pretty good too. I have an older, semi-pro microphone I'll connect when I need to record my voice or chat in a game. So not a point of consideration in my case.
Now I'm researching the best PCI sound card to use in an older Intel motherboard. No PCIe slot available, so it has to be PCI. And I'm going to add a cheapo (but well reviewed) pre-amp for the headphones. Probably overkill for what I'm doing now, light gaming and such, but I plan to try my hand a transcribing speeches and they say the better your sound system, the easier that is to do.