Like I've mentioned earlier, it was pretty easy to tell that my control arm was bad. Just jack up the front wheel and try to shake from side to side. If there is play in the wheel, watch the ball joint on the control arm as you shake it. There was considerable play in the ball joint. Once I replaced it, it was tight as can be.

That being said, I have another hollow sounding clunk to deal with. Like another poster mentioned, if the car has 50K+ miles on it, it might not be a bad idea to replace the sway bar links anyways.