need help, headset microphone doesn't work

i got a headset named icemat audio, or something like that, and i got a brand new vista comp, there is no install cd for it, it's a newer model, so it should work for vista, it does for my step-brother, so well, i wonder if anyone knows what's wrong, this is my first vista pc, and i got it yesterday, when i moved to my own apartment

the drivers installed automatically

first, there used to be 2 accounts, 1 admin and 1 other, which i removed yesterday, the mic worked on the other, but not on the new, when i think i used same settings

so, please tell me what i did wrong? i tried changing everything, but since it didn't work, i re-set the microphone settings, etc