Update:
Bad battery. Tested the battery at home, was reading .6 volts. Then took the battery down to autozone, .55 volts. Replaced the battery, turns out it had a 7 year warranty, so they took 7 dollars off the new one (nice!). Hooked it up at home, started it up and no more noise. Drove down to autozone again and had them test my charging system, everything is normal. The guy at autozone said that a noisy alternator can be caused by a very low battery (basically the alternator is working overtime to maintain a charge). I didn't know that...
Thanks for the input all.
