Sound provider??

[Dustmann]

I was playing Neverwinter Nights for the first time and setting up the audio, it lists a number of Audio providers. I've noticed different selections in many games. The list is
Aureal A3D Interactive
Creative Labs EAX
Creative Labs EAX 2
Creative Labs EAX 3
Directsound 3D Hardware
Directsound 3D Software
Directsound 3D Software Light HRTF
Directsound 3D Software Full HRTF
Directsound 3D Software Pan and Volume
RAD Game Tools RSX 3D audio
Miles Fast 2d Positional Audio
Dolby Surround

Can someone give me a brief background on each or what the difference between them is or at least tell me which one is best?

-edit: my setup is an Audigy 2 zs with Z-680s

[SonicVanguard]

It would take forever to detail or even give you a quick synopsis of all those. To keep things simple, with your Audigy2 and 5.1 speakers, select EAX3.

Dave.