Weird sound problems in games

I have an AOpen AX45H-8X Max motherboard with onboard RealTek AC'97 5.1 sound. I have installed the latest drivers from RealTek and DirectX 9.0b. In the AC97 Audio Configuration window it says that the controller is SiS(7012) and the codec is ALC650.

Also, in the configuration, there is a utility for testing the sound, with a sound source moving in circles around the listener. The _direction_ of the sound sounds as expected, however when the _distance_ changes, there is no change in the loudness.

In games, there is a similar problem. Sounds like winds, a small fire, running water, etc can only be heard when the source is within the field of view. Also these sounds do not fade in as you move closer, but suddenly go from zero volume to full volume the instant you move with a certain distance.


Is there some alternate drivers that can be used or something, or is it best to get a real soundcard like an audigy?