Radeon 5450 no hdmi audio

I don't know if it's the case with your card, but I have seen some Radeons that have a jumper on the card to either select or disable HDMI sound.

You might check and see if your card has such a jumper. I have seen a 4670 with one.

What might that look like? Do you have a pic (im not seeing anything in google) or can you describe it?

If you look at the photo of hte 4670 on this site, you can see the jumper about halfway between the backplate and the pins:

http://houston.craigslist.org/sys/3272796246.html

I just took the time to install this card in my newer windows 7 machine and after installing the included drivers it worked first try so, its not the hardware.

I have no idea why it wont recognize the audio on my htpc running windows xp.

What I did notice was when I did the catalyst custom instal on my windows 7 machine it included the HDMI audio drivers but, when I did it on my older XP machine they were not shown as an option.

Its almost like it thinks the XP machine does not need the HDMI audio driver even though it obviously does.

And yes, I have manually installed the HDMI audio driver but it makes no difference. its almost like it ignores it.