I had the same noise with my 97 Lumina, paid $245.00 to have the power steering hoses replaced. The noise was still there, my mechanic said there may be a little air in the system it will work itself out. After few days I replaced the power steering pump myself. I noticed that the only thing that was damaged and causing noise, was the seal that is on the power steering reservoir. I don't have any leaks or noises since then. You can get the seal set from a part store for about $8 or the whole power steering pump for $40. I suspect when you replaced the belt, somehow the reservoir was disturbed and now it's pulling air and making noise.
Good luck.............................................. ....