were important for a couple of reasons and without them in the story quite a few things could have been different.

1) Denethor, looking into the palantír of Minas Anor, ended up going crazy and killing himself which deprived Gondor of valuable leadership at a critical time (not to mention making Faramir the new Steward).

2) Saruman, using the palantír of Orthanc, got caught by Sauron and became evil. This may not have happened if he hadn't been looking in the stone. Or perhaps his looking in the stone was a final catalyst to his already present trend away from being on the good side.

3) Aragon took control of the palantír of Orthanc and saw the fleet of the Corsairs that was on its way to attack Gondor. Having this knowledge determined what course of action he took and by defeating the Corsairs he was able to gain victory at the Battle of the Pelennor Fields. If Aragorn hadn't known about the fleet from his using the palantír, Minas Tirith may have fallen to the enemy.

just a few thoughts on that. I'm sure others can add more. *s*

as for gold vs. silver...that I don't know about.