Do I need a Sound Card?

I am wondering how I can get at least 5.1 to be sent to my sound system. Here are my specs:

-ECS A780GM-A mobo (AMD 780G chipset w/ Radeon HD 3200 integrated GPU)
-ATI Radeon HD 3470 PCI-Express GPU
-NOTE: I use AMD's 'hybrid crossfire' that uses both the integrated GPU and discrete GPU
-AMD Phenom X3 8750
-Sony X10S blu-ray drive
-Sony Bravia 40V4100 LCD TV (1080P)
-Sony HT-CT100 sound system
-Cyberlink PowerDVD 8 Ultra (supports blu-ray, DTS-HD, etc)


I connect the system via HDMI to the Sony sound system which forwards the video over HDMI to the TV.

I can only get the system to send 2-channel PCM output to the sound system. The sound system is a 3.1 setup so I would at least like to send 4-channel PCM or Dolby Digital/DTS/ProLogic to it (the sound system supports both methods). I am worried primarily about blu-rays since that is when I want this type of sound.

Also, the mobo has an HDMI port and the discrete card comes with a DVI to HDMI dongle. I currently have the HDMI coming out of the mobo's HDMI slot since this is the way hybrid crossfire makes it work.

Is there a way to get my HTPC to send more than 2-channel PCM output with my current setup? (Through PowerDVD, or setting up the HTPC config differently, etc)

If not, what would be the best way to achieve this? (buy a new video card, buy a sound card, etc)

Thanks for your help.

Thank you renethx. I bought a HIS IceQ Radeon HD 4670 and boy is it quiet and powerful. My Vista score is only limited by my processor now at 5.6. Audio works too, it will do up to 7.1 PCM and will pass through Dolby Digital 5.1 and DTS bitstreams with no problem.

Note, to get the audio to work, you have to goto the RealTek web site and download the PC HD Audio ATI HDMI Audio Device. Here is a link to a mirror: 202.65.194.211/pc/audio/HDMI-R203.exe (you will have to place an 'ftp://' in front since I'm not aloud to post links yet).

Good luck to everyone!