Realtek AC97 Audio Driver is a System Utilities software developed by Realtek Semiconductor Corp. After our trial and test, the software is proved to be official, secure and free. Here is the official description for Realtek AC97 Audio Driver:

Edit By BS Editor: Realtek AC97 Audio Driver WHQL for Windows 98/Me/2000/XP/2003(32/64)
The Driver Package A4.02 was released by Realtek at 2008/2/1. This Driver has passed Microsoft WHQL Certification, and is strongly recommended.

It supports following Realtek HD Audio Codes: ALC100, ALC101, ALC200, ALC201, ALC201A, ALC202, ALC202A, ALC650, Realtek ALC655, ALC658, Realtek ALC850.
Please see the Details in Readme.txt.
intel ac97