yep a clay bar will do wonders for you, Make sure you put on a good wax after you get done with the clay barA clay bar is the best way to get rid of water spots. The clay bar will come with a solution that you spray on the truck and it acts like a lubricant. You then rub the piece of clay all of the truck and it will remove all the crap that has accumulated on the paint of the truck. This will leave the truck with really smooth feeling paint.
Hope that helps,