Check the level of your power steering fluid before you commit to the alternator. The reservoir is right behind the alternator and I also believe the pump is in that area too.

Reading on these forums, I've learned that a whine with low power steering fluid (or a bad pump) is a common problem on these cars, and I had the same problem, I thought it was the alternator or belts, but I checked and the ps fluid was so low it was barely reading on the dipstick. Topped it off and the noise is gone.