Changing default sound device for diff programs

This isint exactly FS related but pretty close. Here is the deal, I like to listen to Napster while controlling on Vatsim with ASRC. Napster only routes through the Default audio device defined by WinXP. ASRC's sounds (things that alert you if you have a private message or things) go through the default audio device by winxp also. I want the ASRC sounds to go through my USB headset. So basically is anyone aware of a program that changes the default audio device (emulating winxp) for specific programs. So I can fool Napster to think my soundcard is the default, and ASRC my headset.Thanks