Problem With Realtech audio drivers

I am using an Asus M2V mobo which has an onboard Realtech ALC660 audio chip.
Vista installs its own HD audio drivers which don't work and using windows
update is no good as it just reports that I have the correct drivers !!. I
have downloaded the latest audio drivers from Realtech and installed. These
work perfectly until reboot and the drivers revert to vistas hd audio again.
There is one other post from a guy with the same problem which is unresolved.
Anyone like to make any suggestions please ?