I had a high screeching sound that began after driving about 30 minutes. Turned out to be my tie rod end that went bad. I was able to reproduce the sound when I turned my steering wheel when car was stationary, at which point I knew for sure.

Here is a link to my how to guide for others interested in trying. Shouldnt take more than 30 minutes.

http://www.ehow.com/how_5029666_chan...rods-audi.html