Audacity: Can Audacity record RealAudio or other streaming audio?
"With most Windows and Linux audio devices, it is possible to record whatever sound the computer is currently playing, including internet radio streams.
In the drop-down menu on Audacity's mixer toolbar, choose “Wave Out” or “Stereo Mix” as the input source. (The exact name may be different, depending on your computer's sound drivers.) When you press the Record button, Audacity will capture whatever sound is playing on your computer's speakers.
If this doesn't work on your computer, you can instead 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."