Ah. That's probably going to be the problem, then. Mine came with those adapters, which seem to be a bit special. Could have to do with the type of DVI end it has (you can see a lot about DVI formats on the wikipedia entry). Still, try the instructions I sent you. They should work, one would think. As you can see, there are extra steps one must take to get the audio.
If it doesn't:
This is an example of the product (though I'm not 100% sure that would work): Shoptopia.com.au - ACTIVE DVI TO HDMI ADAPTER - Computers >> PC Accessories
You'd need to make sure what you got kept the audio line open, which is unlikely in a straight conversion cable.
I'll look around and see if I can find a way to purchase what came with my card.