How can you tell if the cv joint is bad? Apparently I have a bad CV joint in one of the front half shafts, which could be returned to the store since they have less then 300 miles on them. Is there anyway to determine the bad one without having to remove them both?

To check a CV joint, slowly drive the car at full turning radius (like in a cul-de-sac). Listen for any "clicking" noises coming from the wheel area. This is a sign of a failing (loose/worn) CV joint. Full left turn to check the left wheel, full right turn to check the right wheel.