[wiswind]

The fluid is going someplace....you will want to find where. Perhaps it is leaking at a high pressure point....only when you are driving?
The steering rack is toward the rear of the bottom of the engine.....and the power steering cooler is in front of the radiator......point being.....there is a lot of territory to look.....

If the fluid has gotten low...it is very likely that you have gotten air into the system....which will make noise. The way to purge the air from the system is to turn the wheels fully in one direction, to the stop, and then to the other direction to the stop....do not rest against the stop....just touch it and then turn the wheels the other way.

Also, make sure that you use the correct fluid.
I think your 2001 calls for a Mercon Transmission fluid for the power steering.
If so, I would recommend Mobil 1 Mercon (can be bought at autozone).
Another recommendation would be Redline Power Steering fluid....but not as easy to find.