My P5L-MX is using Analog Device AD1986A chip set from SoundMax. I might need to wait for them to update the drivers in future. I have tried the beta version but Windows 7 said not compatible.
I have the driver disk from Asus come with the board that has XP drivers. It doesn't work with Windows 7. I have another old machine (build in 2004) running AMD 1.7G that all drivers installed without any problem. Wonder why somebody don't like Vista and now Windows 7.