Vista - Problem with 5.1 surround sound

Hello,

I have a TerraTec Aureon 5.1 Fun sound card. Divers are v5.12.1.639, signed
by Microsoft (and installed during Vista rc2 installation).

I have configured the speakers in 5.1 surround with the Speaker Setup
pannel. Then I launched the test and all speaker work well. When i clic on a
speaker picture, the sound comes from the good speaker.
But my problem is that even the good configuration, all sound on windows,
mp3 playing with wmp11, DVD watching with wmp11 or gaming with game designed
for 5.1 surround sound.... i always got a stereo sound with only my 2 front
speaker (front left and front right). After testing almost all application
with sound, i never got 5.1 sound, only in sound configuration pannel.

I'm disposed to give any other information to help to fix this issue.

Some informations from dxdiag :

------------------
System Information
------------------
Time of this report: 10/27/2006, 18:06:18
Machine name: DARKCITADEL
Operating System: Windows Vistaâ„¢ Ultimate (6.0, Build 5744)
(5744.vista_rtm_edw.061003-1945)
Language: French (Regional Setting: French)
System Manufacturer: ASUSTeK Computer INC.
System Model: A7N8X-E
BIOS: Phoenix - AwardBIOS v6.00PG
Processor: AMD Athlon(tm) XP 3000+, ~2.2GHz
Memory: 1022MB RAM
Page File: 710MB used, 1602MB available
Windows Dir: D:\Windows
DirectX Version: DirectX 10
DX Setup Parameters: Not found
DxDiag Version: 6.00.5744.16384 32bit Unicode

-------------
Sound Devices
-------------
Description: Speakers (TerraTec Aureon 5.1 Fun)
Default Sound Playback: Yes
Default Voice Playback: Yes
Hardware ID: PCI\VEN_13F6&DEV_0111&SUBSYS_1144153B&REV_10
Manufacturer ID: 1
Product ID: 100
Type: WDM
Driver Name: CMAUDIO.SYS
Driver Version: 5.12.0001.0639 (English)
Driver Attributes: Final Debug
WHQL Logo'd: No
Date and Size: 7/16/2002 02:58:12, 379726 bytes
Other Files:
Driver Provider: TerraTec Electronic GmbH
HW Accel Level: Basic
Cap Flags: 0xF1F
Min/Max Sample Rate: 100, 200000
Static/Strm HW Mix Bufs: 1, 0
Static/Strm HW 3D Bufs: 0, 0
HW Memory: 0
Voice Management: No
EAX(tm) 2.0 Listen/Src: No, No
I3DL2(tm) Listen/Src: No, No
Sensaura(tm) ZoomFX(tm): No

Description: SPDIF Out (TerraTec Aureon 5.1 Fun)
Default Sound Playback: No
Default Voice Playback: No
Hardware ID:
Manufacturer ID:
Product ID:
Type: WDM
Driver Name:
{0.0.0.00000000}.{129189ad-9578-4844-a4b6-82e8be5bae85}
Driver Version: ()
Driver Attributes: Final Retail
WHQL Logo'd: n/a
Date and Size: , 0 bytes
Other Files:
Driver Provider:
HW Accel Level: Basic
Cap Flags: 0x0
Min/Max Sample Rate: 0, 0
Static/Strm HW Mix Bufs: 0, 0
Static/Strm HW 3D Bufs: 0, 0
HW Memory: 0
Voice Management: No
EAX(tm) 2.0 Listen/Src: No, No
I3DL2(tm) Listen/Src: No, No
Sensaura(tm) ZoomFX(tm): No

--------------
System Devices
--------------
Name: TerraTec Aureon 5.1 Fun
Device ID: PCI\VEN_13F6&DEV_0111&SUBSYS_1144153B&REV_10\4&2BE12347&0&4040
Driver: D:\Windows\system32\drivers\cmaudio.sys, 5.12.0001.0639
(English), 7/16/2002 02:58:12, 379726 bytes
Driver: D:\Windows\system\crlds3d.dll, 4.12.0001.2002 (English),
10/20/2000 10:28:00, 765952 bytes
Driver: D:\Windows\system32\a3d.dll, 4.12.0001.2008 (English), 11/23/2001
04:08:20, 712704 bytes
Driver: D:\Windows\system32\Audio3D.dll, 4.12.0001.2008 (English),
11/23/2001 04:08:20, 712704 bytes
Driver: D:\Windows\system32\cmnprop.dll, 5.00.2195.0011 (English),
3/29/2002 06:52:46, 32768 bytes
Driver: D:\Windows\system32\drivers\drmk.sys, 6.00.5744.16384 (English),
10/4/2006 08:24:02, 130048 bytes
Driver: D:\Windows\system32\drivers\portcls.sys, 6.00.5744.16384
(English), 10/4/2006 07:54:58, 167424 bytes

I Would Say that you use the windows XP Drivers beacause The Windows Vista Drivers Don't Support 5.1 for some uknown reason