Try right clicking the little loadspeaker (sound) icon to the left of the clock. Choose to Open Volume Control and make sure the MIC is unmuted. Then check if the MIC is plugged into the correct output jack. She can then open Sound Recorder to check its operation.
I have a friend running XP.She added a external mic. Can anyone tell me how i may go about turning it on using XP. I run a mac with OS X and we don't have these problems. But i would like to help her get it working.