Get a new battery. Im pretty sure this is your problem.
I can safely assume that your 02 still has the original battery.
If it is a bad alternator, im sure you wont be able to drive your box home that night since it will drain your battery and will eventually stall.
P.S.
Just to check on the "health" of your alternator after you change your battery. I would advise you to bring your car to Autozone AFTER you change your battery and have them check your alternator. (it is actually a battery and alternator test). I usually do this with all my cars- freebie battery/alternator check
