Virtual Audio Cable - Linux and Windows

If your looking for a virtual audio cable (VAC), thats free, open source and works on Linux, Windows and OSX check out jackaudio. For some reason this neat bit of software doesn't get nearly the attention it deserves and despite what you'll read out on the net, it most definitely does work on Windows (even Windows 7, 64 bit). Its really simple to use, just:

Install it.

Start Jack Control (will come up in your list of programs after the install).

Go into the settings, and select "portaudio" as the driver.

Start Jack Port Audio.

Restart Jack control.

If you right click on the sound control icon (on the far right of your task bar), and select recording devices, you should see a new device called "Rec. Playback". You can record from this device and it will capture the sound from your sound card. (Note you have to set it to the "default" recording device if your just using the standard windows recorder). If you need any fancy routing, you can specify what you want where in the "Connect" screen within Jack Control.

Theres ALOT of other options, none of which I've played with but for just recording your soundcard output to a file this will do the job well.