[Kalimac]

I agree with Eomer - it would have happened, just not so quickly and efficiently. Saruman spent a long time studying the art of the enemy, originally in order to use it to fight him, but he seems to have fallen into the trap wherein if you try to think like your enemy for too long, you end up by becoming your enemy. Without the Palantir he probably would not have been as actively opposed to the forces of Gondor and Rohan, but he would have done his best to make things sticky, to wring some sort of advantage out of it.

In fact, when you think about it, his lack of a palantir could have been a stroke of bad luck for Gandalf & Co. Saruman seems to have had the ring-lust before he had the Palantir (at least, he counseled against others searching for it, possibly so he could have a shot at it himself) and had he not been emboldened by his communication with Sauron, he might not have shown his hand so early. Gandalf may even have given him information about where the Ring was, and who knows what the result of that would have been.