In Windows 7 and Vista, you can adjust the microphone volume in the Windows Sound Settings, which can be found by doing either of the following:
• Right-clicking the speaker icon in the taskbar and selecting "Recording Devices".
• Navigating to the Control Panel and selecting Hardware and Sound > Sound, then selecting the 'Recording' tab.
Once at this screen:
1. Select your PC's Line In/Microphone Input, then click the 'Properties' button.
2. When the 'Microphone Properties' window appears, click the 'Levels' tab. You will see two separate controls: 'Microphone' and 'Microphone Boost'.
3. Adjust the microphone volume to your liking.