Hi juli.chavez,
Have you tried the microphone in another computer to verify whether the low volume is to do with the microphone or not?
If the microphone works well in well in another computer, then the problem lies with your computer.
Try with a different microphone on your computer and see if it works. If so, then the problem lies with your microphone.
Check whether increasing Microphone Sensitivity and Un-muting the Microphone helps. And get the latest update of your audio driver. Follow the steps 4 and 5 from the thread below posted by Rehman F - Microsoft Support.
You may also follow the troubleshooting steps in the links below.
Troubleshoot audio-recording problems
http://windows.microsoft.com/en-GB/windows-vista/Troubleshoot-audio-recording-problems
Tips for fixing common sound problems
http://windows.microsoft.com/en-US/windows-vista/Tips-for-fixing-common-sound-problems
Hope this information is helpful.
Regards,
Shinmila H - Microsoft Support
Visit our Microsoft Answers Feedback Forumand let us know what you think