Watching neighbor's Shih Tzu?

I have a 20 pound Maine Coon (He is NOT declawed). My neighbor has asked me to watch her little Shih Tzu for a week over Christmas while they go away. PLUS I have a 5 year old child that may be traumatized if it ends badly. I said yes on the condition that the animals meet first and get along.
Does anyone have any tips on the introduction and getting the animals to co-exist peaceably if I were to keep the dog for a week?

Has your cat met any dogs before? Is he the kind to stand up for himself? Given the size difference here, I'd acutally be concerned about the dog getting injured. The dog will probably want to stay close to a human for the whole week making it easier to keep an eye on them. Will you be home for the whole week? Is there a spare room you could put the dog in when needed (or a crate) to keep them both safe if no one's home.
It's hard to say how they're going to get along without knowing them, but I know tons of dogs who are good with cats. My cat on the other hand attacked the last dog I brought home to visit!

I have had the dog since Thursday. I have a crate for the dog and she is crate trained very well actually. She stays in there when we leave the house and she sleeps in there at the foot of my bed. It's going alright but I don't trust them alone at all. The cat's toleration of the dog has improved but he hasn't warmed up to her at all and if she comes too near he attacks. He doesn't full on attack but gives a good warning swipe. The problem with this is the dog thinks this is play and great fun. I am afraid it won't go well at some point but so far it is copecetic and I guess it's the best I could hope for.

Gosh, when I first read this (just a couple of minutes ago), I guess I figured your neighbor meant would you just go over to HER house and take care of her fur baby over there!  That's what I do when my neighbor who has dogs goes away.  I just go over there several times a day to let them out, feed them, spend time with them, put them to bed, etc.  It's a chore, but she then does the same thing for me when we go away...PLUS we feed raw, so she has to deal with that on our side.  I figure it all works out in the long run. 

I'm kind of surprised she expected you to actually take her dog into your home with your larger than her dog cat .  I guess it's a very good thing the dog is used to being in a crate.

Oh yeah, we have full on adopted the Tsu for a 8 days. It's definitely a change but I'm pretty easy going and just rolling with it.