I need help with my mic

Im using a Logitech head set with the mic attached and i cant get it to work im mostly trying to use it for ventrillo i have it attached to the back of my comp its not a usb it has the mic cable and the speaker cable both plugged in the right spot idk whats the problem i go into my volume controls/properties and im using Sigma tel Audio as mixer device when i try and look for mic there is none so i cant see if it is muted or not please help.

I had the same problem until I bought a dedicated soundcard with a microphone input. The gain on the microphone port was adjustable on the soundcard. I bought a Creative Labs X-Fi Extreme music, but I imagine most soundcards will work.