Will SigmaTel High Definition Audio Codec work on Windows Vista RC1

I had added Windows Vista RC1 in my system. It is entirely a new OS which I installed over XP. Now the system works quiet nicely. The drivers are updated. I am not getting audio in that. I use a microphone for voice chatting. It works, but due to some reason there is no audio hardware listed. I checked inside Device Manager and found the problem. The driver failed to work with Vista RC1. And along with that I will also need a proper codec pack that can fix the issue. From where can I download SigmaTel High Definition Audio Codec to make my system respond properly.

I am having a similar sigmatel audio chipset in my Gateway M675 laptop. I had formatted the same and installed Vista on it. This cause driver failure in the system. I tried to find the same from official website. There is no driver provided for Vista. Atlast when I found nothing I went to re-install back Windows XP on it and it started working.