I am sure someone else will chime in but I don't think it was ever completely decided if the zetec is not interference or not. I think most feel it isn't and I agree since I think all ford engine are non-interference.
do remeber Ford was the one that said the belt was good to 80k most likely updated from 60k. Ford has said it will last the life of the car, and with most people selling cars before 100k that is the life of the car to them.
if you plan to keep your car for awhile and want peice of mind, just change the timing belt and then you don't have to worry.
I changed mine at 104k on my 95 and the belt looked very good. the issue would have been the tensioner was about to split in half. make sure you change all the plastic pullies also.
other will say to change the water pump since it is easy to get to while changing the timing belt, that is your call.
