Vizard supports 3D sound through the Windows DirectSound API. The position and orientation of the sound source and listener are processed by its 3D algorithms. The resulting sounds will have a direction and be louder or quieter depending on their distance from the user.
Not much is required to add this in the Vizard code, simply call the playsound command on the node you want to attach the sound to. For the spatialization to work, mono .wav files must be used. See the 3D sound tutorial for an example script you can run.
Where spatialized sound is concerned, a discreet sound card will not buy you anything in terms of processing over an integrated sound processor. What it will buy you is potentially better sound quality from
There can be differences in the spacialization depending on the sound drivers used. Some drivers provide their own utilities for configuring 3D sound properties.
If using speakers, a 5.1 surround system is one of the best options for improving spatialization without making a large investment in hardware.