i got them from radio shack. the adapters are stereo, but i have extension cables that are mono. so i go from headset to 2.5mm->3.5mm adapter to extension cable to computer. and then computer to extension to 3.5mm->2.5mm adapter to controller.

if you're just talking in the mic and trying to hear yourself, in the windows sound settings you have to turn on the "listen". if you're doing it through the program, the listen has to be on in that.

also, i've noticed that you have to have all the adapters and stuff hooked up and then the last thing to do is plug it into the computer. mine doesn't recognize the mic if i plug the extension in and the plug the mic into that.