Squaling Noise with A/C on.

I just bought a 2004 Nissan Maxima 3.5L DOHC w/ 128k Miles. Runs GREAT, Super Fast! Just one problem... When I start the car with the A/C on, I get a loud high pitch squealing noise coming from what I assume is my belt area. But it is only when i turn the A/C on. If I turn the A/C off, the noise goes away. Vis versa.