Thanks Digicidal, I'm all for HDMI, I've been chasing a proper HDMI solution for a while as I am very aware of the advantages. My current setup uses an nvidia 7300 GT AGP, no HDMI and no digital on-board sound. This is why I went for the Auzentech. Power on this machine is lacking though, and the Pentium D generates a lot of heat so the fans are always loud. This is why I've sought out the 7800, since it fits in my cabinet, has enough power and is dead quiet. I also know that it will run Ubuntu flawlessly. Of course the really important thing is the PCI-E for the HDMI graphics,
What I didn't realize (see my first post) was that the newer graphics cards have integrated digital audio for feeding the HDMI. This changes everything, as it means I don't need the sound card any more. I thought I would have to use the S/PDIF header on the graphics card to provide the audio from the sound card (or the motherboard for the lucky ones). I must admit, I had to look really hard to figure this out. It was only when I started looking at the Linux forums that I found the info about the audio devices on the graphics cards. For some strange reason I just didn't see any information about this on the manufacturer's websites. Maybe it's just me.
I will probably end up getting a GT 210 fanless as I refuse to use ATI because of their appalling support for Linux. I use the GT 210 in a DC7900 at work and am very pleased with it's performance. Let's hope it does just as well for the HDMI HTPC task.