Anyone remember that sad incident in which the dog killed his master's 2 year old kid?
Theres been countless incidents where the dogs saved kids, and grown ups too... You cannot question a dogs loyalty... As for some incidents where terrible stuff has happened, remember human beings have killed 2 year olds too, probably alot more times than dogs.
I was once pulling in infront of my house, and these three guys all of a sudden came upto me and tried to get my watch and phone (something thats becoming more and more common these days), and the next thing I know two of them are on the run, and one of them down with his shalwar in my dogs jaw! Before that incident, my whole family was opposed to keeping a dog! It all changed of course.
TLK, go for it, just make sure you take the necessary precautions, make sure the dog is dewormed and clean. Beware though, keeping a dog can be a very tedious job at times, financially as well, and theres always an emotional attachment to the whole thing. When we had to put our dog to sleep after 12 years because he was in pain, it was very hard for us, and this is something your kids will have to put up with later too.