Can't re-enable microphoine array

Folks-

I run run Vista Home Premium SP2 on a Dell XPS M1730 with built in

microphones(2). I inadvertently disabled the Sigmatel Hi Def Audio

microphones from:

CONTROL-PANEL\SOUND\RECORDING\CONFIGURE

I expected the microphone array would appear with a CONFIGURE option to

enable it...but it no longer appears under RECORDING and I can't figure out

how to get it back. Any suggestions?

Thanks.

-Gary