ACTION: In Winamp: Options menu > Preferences... > ("Plug-ins") > ("Output") > Nullsoft DirectSound Output > Configure > (set device to Line 1: Virtual Audio Cable)
VAC is running invisibly in the background, waiting to transfer audio signals for you to where you direct it. This transfer conduit is called "Line 1". You can optionally create more lines to send audio to other software, if you decide to get more complex with your audio.
In the steps ahead, we will use "Line 1" from Winamp to be the input into your new Ventrilo user name.