Mystery File

I have a driver being installed for an AC79 onboard, laptop chipset. I view
the details and get the name of the file... ac97intel.sys (intel chipset).
I'm shown the location being in system32\drivers. Yet I can't find the file.
Why?

I have a Analog devices chipset for AC97 audio(AD1881) and am trying to get
full use of that codec. But it's next to impossible with Vista always
reinstalling its most favorite driver.

I have had success with the Soundmax driver so I know it works. But
installation is not a sure thing for whatever reason. So I would like to
isolate the Vista choice and feed Device Manager my choice... which I know
works.

Thanks for any help.