Engine noise while turning

My 2000 Cavalier has this new noise that's come up in the last few days.... when I turn to the left, and am going at a decent speed (at least 25, I'd say), it makes a high pitch screeching noise. I don't know if it does the same thing when I turn to the right. Any thoughts are appreciated.

I checked the power steering fluid, and it was a little low so I topped it off. I drove it to school today (45 mile round trip) and it was still making the noise when I got home. I'm not sure how long it would take it to stop making the noise if, in fact that was the problem.

It only seems to make the noise when turning to the left, not the right. It seems to me it could be the brake pads. Any other thoughts though?