there's no way to mute the computer speakers?
i have a seperate mic that plugs into the mic spot on my soundcard or mobo.
but i think i understand what you want. you want all voice communication over your headset while other sounds out of speakers.
im not sure you can set this up. it wouldnt be hardware, it would be software. i havent heard any games allowing this but i havent realy looked.
it might not be possible.
it wouldnt depend on your headset though, usb wouldnt have any impact on the situation. you need the program(game) to send seperate sound to the headphone jack and speaker jacks and then your mobo's sound or soundcard would have to output them both. seems tricky