I don't know abount that, the driver's date was 2001. My early 00's business dell laptop with XP has this driver showing under Device Manager, System Devices. This driver is not specific to the ATI Radeon HD 5670 video card. If you mean it should allow sound to be passed through the HDMI, that is possible and likley. I have never done this, the speakers are hooked directly to the PCI sound card.
UAA is a class driver for audio devices similar to the class drivers used for USB devices, i.e. a single USB mass storage device class driver can support mass storage devices from many different vendors. It was an effort by Microsoft to provide system-level support for standard sound devices, something better than legacy Sound Blaster compatibility. There's never been a VESA-style standard for audio devices. (Actually, there is: VBE/AI. Heard of it? Me neither.)
Your AMD display adapter may advertise itself as UAA-compliant under Windows 7 without being 100% UAA compliant. As I said earlier, Nvidia ships its own audio drivers. I don't know what AMD does. It's unfortunate that neither worked properly under Windows XP, but it's not surprising given the age of Microsoft's driver and their inability to validate future hardware before it's manufactured. They need the right kind of Doctor. ;-)
