You'll also want to check the selected audio input device and enable the microphone +20dB Boost if necessary...
Double click the Sound icon in the system bar next to the clock to bring up the Volume Mixer. To enable the +20dB boost is annoyingly dependant on your sound card. You may have an option for the microphone on the window by default as below. If you don't see the "Advanced" button then select "Options" and enable "Advanced Controls" if possible. When you click the "Advanced" button there should be an option for "Microphone Boost." or "20dB Boost" or similar. If there isn't an advanced controls option then no worries, it may be under the recording controls, as below.

Next you'll need to check the audio recording device selection, you'll need to go to options and under "Adjust Options For:" select "Recording." There you should be able to check which device is the recording device (Line In, Microphone, etc) and if the 20dB bost was not in the previous section you should be able to enable it here by the same method.
