Yup, just to second that advice - the Kathy Love book is biblical, well worth a read.
And in the spirit of conflicting advice (as mentioned above), I've only ever used tap water for my snakes, and I'm inclined to think water conditioners are much better for the shop's revenue than they actually are for the snake.
You'll often come across conflicting information on this form - and with good reason. There isn't always one single 'correct' way to do things. Different approaches in rep keeping can be just as effective as each other, what you have to do is weigh up the strengths of the arguements for and against a particular aspect and then make your own mind up about what you want to do for your snakes.
Here's a recent water-based thread to illustrate the point.