Just tighten the belts a bit more, and check it periodically. new belts will "form fit" your pulleys a bit and in effect loosen. I just replaced mine and that was the exact problem (as far as the screeching goes). As for ps pumps, mine needs the new O ring, but it doesn't squeak, it whines/grinds and is awfully loud. Is your ps pump loud? or is it just the belts at cold start? If its only at cold start, just tighten the belts a bit more. They should have a good resistance, but nothing crazy!
