Serpentine belt replacement huh? I just had an experience with that puppy. Here's my How-To list that I posted on another topic. This applies if you have a 2.0 Zetec:
My advice, to get that belt off:
1. Jack the car up, and take the passenger side wheel off
2. Get yourself a 13mm wrench, and a foot long pipe to fit over the box end (not the open end)
3. Take off the Drivebelt guard (it's got two bolts on it, you'll see it) and put the open end of the wrench on the tensioner pulley. Then put the pipe over the wrench
4. Fervently pray to God that the wrench won't dig through your hand while you're pulling on that tensioner (it should go clockwise to release the tension, so pull down). Get a friend to help you pry the belt off of the alternator pulley.
5. After you take off the belt, look on your passenger side strut cover. (I think that's what it's called). You'll see how to route the belt, which will differ depending on if you have A/C or not. Pull that tensioner after routing it, then go inside, grab a Budweiser, and watch some NASCAR
I have to get these fixed sometime soon that is why I am asking the price of what others think. Oh yeah and i need a new serpentine belt.