I'm pretty sure I have a bearing in one of my pulleys going out...makes a squeeking sound...would this cause my engine to vibrate? Pulley unbalanced?

 

Post a video on YouTube so we can hear it.

 

I also have a 00 neon with 178K miles. I hear the tensioner pulley goes out often. You could remove the alternator belt and run the car just long enough to confirm or eliminate it. The serpentine belt has the tensioner pulley, A/C compressor, and power steering pump. You might try removing the belt and spinning each pulley checking for noise or play in the pulley bearings.
Do make sure your belts are in good shape and taunt before trying to isolate the noise.