A partir do Windows Vista, esse recurso parece ser suportado nativamente :
Take surround sound on the road
In addition to taking advantage of high-definition audio with speakers, you can also get the best possible sound when you're listening to music or movie audio through headphones.
Windows Vista includes a feature called Headphone Virtualization that uses technology called Head Related Transfer Functions (HRTF). HRTF uses information about the physics of your head to create a virtual surround sound experience through your stereo headphones. When listening to music or movie audio with Headphone Virtualization, you might feel like the sound is transcending the headphones, providing a listening experience that includes hearing sounds from front to back, as well as side to side.
To set up Headphone Virtualization
Open Audio Devices and Sound Themes by clicking the Start button, clicking Control Panel, clicking Hardware and Sound, and then clicking Sound.
Click the Enhancements tab, and then click Headphone Virtualization.
Se esta opção parece estar faltando para você, e você tem uma placa de som RealTek, pode ser necessário usar o RealTek Audio Manager, clique com o botão direito do mouse na porta analógica atualmente atribuída como saída do alto-falante e retoca-o como fones de ouvido .