Humming from front/left?

Hi,

Here's the situation.

When I go above 50mph in my '94 Pontiac Grand Am, I hear a humming sound from the front/left of my car.

I'm thinking wheel bearing or power steering drive belt?

I have a serpentine belt... and it's in rough shape, I think, cause it squeels and squeeks a lot.

Could this be related?

Or is it just a wheel bearing?

The humming sound gets louder when I turn left and also seems to get higher pitched when I go faster.

How dangerous is this and how much would it cost to get fixed?

Thanks!