Record computer sound without using microphone

I tried to record computer sound without using microphone, such as online music.
1) One possibility is to use audacity, which can be downloaded from:
http://audacity.sourceforge.net/download/
First we need to set the record device as  "Stereo Mix" in Windows 7
Start->Control Panel->Hardware and Sound ->Sound->Recording
Right-click anywhere inside the Recording tab and choose "Show disabled devices" then right-click again and check "Show Disconnected Devices"
"Stereo Mix" show up, right click it and enable and set as default Go to  audacity, and select microphone as "Stereo Mix" 
Reference:
http://audacity.sourceforge.net/download/
http://audacity.sourceforge.net/help/faq_i18n?s=recording&i=streaming 
For some reason, I failed.
2)   use a cable to connect your computer's “Line Out” (speaker) port to its “Line In” port, and use Audacity to record from Line In. But I do not have a cable yet.
3) Freecorder 3.0 is a browser plug-in. It records to lossless WAV or lossy MP3 format direct from the program producing the sound. But it failed for Firefox 17.0.
4) Using virtual audio recorder, which can be downloaded from:
 http://www.virtualaudiorecorder.com/
It works well and the output audio can be .mps and .wav format. Sometimes it sets streams 4 as playback. We may need to set it as earphone or speaker to hear the recording.
5） Finally I found a simple solution. Connect microphone and earphone with jack and use sound recorder built-in in Windows.