I'm not familiar with virtualPC, but I bet with vmware and a hacked kernel I can export to a file.

This is more or less why the "dummy" sparc audio driver exists: realplayer wanted to talk to an audio device, and I wanted a file. So I wrote an audio device that faked it well; if you open it for read data becomes available as it's written.

I wonder what I did with my CDs of radio shows recorded that way...