If you have the money to spend, get a set of good over ear headphones like the Audio Technica M50 or AD7 and then get an Antlion ModMic to use as the microphone. You'll get sound quality miles ahead of the gaming headsets and a really well built microphone. If you have some extra cash to spare still, you can pick up a decent sound card as well with a dedicated headphone amp to help drive those headphones incase onboard audio isn't cutting it for you.
Currently I'm using a pair of Beyerdynamics DT880 (600 Ohm) with an Antlion ModMic and a Xonar Essence STX.
Antlion ModMic:
http://www.modmic.com/
For reviews on over ear headphones:
http://www.head-fi.org/products/category/over-ear
M50's can be had for fairly cheap and are easy to drive w/o headphone amps and have one of the best Price to Performance ratio.