Msi StarCam 370i Sound

Hi, I have just installed a StarCam 370i on my computer also on a friends and my brothers computers. The picture quality is fine but am havin trouble with the sound. This StarCam has a built in microphone which I thought would be great as it would save having to have a mic hanging round my neck!! The sound is very crackly and there are all sorts of funny noises going on while we try to speak, also the voices break up a lot and it is difficult to hold a conversation. We are using Skype v2 which supports video. Has anyone any idea what could be causing the sound problem. Would be very grateful if you could help!