Hi
I don't have a laptop but I use Skype all the time, so this may not be a lot of help.
On my PC if I open Skype and click on Tools, Options, Audio Settings there is a place to configure the microphone setup.
You should be able to select the microphone that's in use on you computer and a green bar will indicate whether it's detecting sounds.
You can check to see if it's working by placing a test call via Echo / Sound Test Service,
Mike