My wife and I just bought a new side by side refrigerator with water and ice dispenser in the door. When we purchased the refrigerator at Sears we also got a kit to put in the water line. The kit has a saddle valve and 25' of copper pipe. I went down to the basement/crawlspace and found that all of the water pipes in our 6 year old house are PVC. Is there any danger in using the saddle valve to hook this up to PVC water pipes? I'm just worried about the saddle valve cracking or breaking th PVC water pipe.

I don't think there is any danger of you cracking the PVC from tightening the clamp to the pipe. It only takes a little pressure to keep it from leaking. And since the pipe is round it is the same principle as trying to crush an egg with your fingers, the roundness protects it from crushing.