The topic explains everything 
I have Vista (yeah, yeah, it sucks. Really. Just testing the Ati card) on my brand new iMac 24 and the audio quality is VERY low. Worst than the macbook speakers. The strange thing is that in MacOSX the quality is good and even in Vista with earphones. I reinstalled the Realtek HD drivers but it didn't change anything.
Do you have the same problem?
I have Vista (yeah, yeah, it sucks. Really. Just testing the Ati card) on my brand new iMac 24 and the audio quality is VERY low. Worst than the macbook speakers. The strange thing is that in MacOSX the quality is good and even in Vista with earphones. I reinstalled the Realtek HD drivers but it didn't change anything.
Do you have the same problem?