sensor - How to determine position from gyroscope and accelerometer input?

I have a 3-axis accelerometer and a 2-axis gyroscope. I intend to measure something that only moves in the X and Z axis. I've heard of using Kalman filters to smooth out the acceleration vectors, but I can't find a good tutorial for a complete beginner to the topic. Also, I know I can double integrate acceleration to get position, but how do I do this with a finite number of sampled acceleration vectors? I would appreciate links to good tutorials for beginners on both these topics.