I just found this from a different section of the forum, so it seems I will only be able to get stereo PCM from the video card.
HD Decoding with UVD
One of the features lacking in the 2900 XT was the new UVD video decoder engine. UVD provides hardware acceleration of H.264 and VC-1 high definition video formats used by Blu-ray and HD DVD. The video processor allows the GPU to apply hardware acceleration and video processing functions while keeping power consumption & CPU utilization low. When the HD 2900 XT was released it took the press by surprise that the low-cost HD 2400 and 2600 where able to post-processes and accelerate HD streams like VC1 and H.264 fine while the 400 USD counterpart missed that engine and thus that translated into much higher CPU utilization.
That no longer the case, we ran a HD-HQV test and noted sheer decoding perfection on both the HD 3850 and 3870. Low CPU utilization whilst scoring a maximum of 100 out of a 100 points. One other improvement has been made as well you can now upscale your 1920x1080 streams fine towards for example a 2560x1600 sized monitor (no more black borders).
HDMI & HDCP compatibility
Obviously the entire HD 3000 series of cards will offer HDMI connectivity with the help of a DVI adapter or native with a HDMI connector integrated into the card, all cards fully support the DRM cancer called HDCP. Unlike most current HDMI implementations on PCIe graphics cards, this HDMI solution also incorporates audio functionality into the GPU.
Your series 3000 card can directly output audio over HDMI – removing the need of a separate sound card over your HDMI connector. Where it'll output that sound in 16-bit PCM Stereo sound or AC3 5.1 compressed multi-channel audiostreams as Dolby Digital and DTS. A feature, especially for those who use their PC as a HTPC and are connecting HDMI towards a HDMI receiver.
So with the Series 2000/3000 you'll receive a DVI-to HDMI adapter which, and make no mistake here, will carry sound over HDMI. That's unlike current DVI-HDMI adapters and cables which do not carry sound. Fantastic if you are watching a Blu-ray movie, simply connect HDMI towards your HDTV for PCM sound, or connect it through a TrueHD/Dolby HD receiver and get that sound lovin' going on through that receiver of yours. All with one simple cable.
Here we can see that DVI to HDMI dongle that is supported with the HD 3000 series Radeon graphics cards.
I have to note that some board partners are now slowly making to move to integrate a HDMI connector on the graphics card. TUL (PowerColor) for example submitted a card today that has HDMI integrated.