Hi,
I'm going to add my own experience ot this post, since recently I run into more or less the same problem. exacerbated by the fact that my laptop doesn't have a mic-in plug. Since my laptop sucks at gameplay, I'm using a desktop as "game" machine and record the commentary on his own on the laptop. I solved the problem using an extra USB sound card connected to the laptop, the sound card is a super-cheap Beyerdynamic USB, however it has two a nice feature: you can set it to 'echo' the microphone input through the headphone output by hardware, this way I can plug the headphone into the PC jack, use an extension to connect the USB interface to the PC and hear both the headphone mic and the game sound in the headphone and second: it has a 'mute' button for microphone.
The USB interface was sold in pair with an associated headphone: a Beyerdynamic MMX-2, I have also another headphone that is a Sennheiser PC 3 (a really cheap one at about 30 euro), that is light enough, has good quality sound and the microphone isn't that bad. The Beyedynamic is a lot more insulating and (supposedly) has a better microphone, but I'm struggling with that because the mic is so sensitive that picks up my breathing.
The good of this setup is that you can use *ANY* headphones you like with it, as long as it as a mini-jack microphone (so, no good with 'big' pro microphone).
None of the two headphones are too bothered by click of the keyboard or the mouse, also, they don't picks up most of the surrounding sound.
Since I record the commentary separately from the in-game-sound I can handle the commentary lately and remove/readjust the sound as I like. I mix all of them into my video editing software.
You can hear the result of it in these two videos:
this is recorded with the Beyerdynamic
https://www.youtube.com/watch?v=kVKXsD7 ... wc&index=2
this is recorded with the Sennheiser
https://www.youtube.com/watch?v=ddFpb7Q ... ct&index=6
For the post-processing I remove the background noise (there isn't a lot of it), amplify a bit the signal and remove some of my mouth noises, in total I don't think I spend more than 20 minutes 'cleaning' the recording.
The USB interface and associated headphones is this one:
http://www.thomann.de/nl/beyerdynamic_mmx2.htm
I can't find the Sennheiser anymore but it looks a lot like this one:
http://en-us.sennheiser.com/gaming-head ... reo-pc-310
Hope this can help somebody else.
Davide