I am trying to figure out how to determine the direction a collision occurs between two rectangles.

One rectangle does not move. The other rectangle has a velocity in any direction. When a collision occurs, I want to be able to set the position of the moving rectangle to the point of impact.

I seem to be stuck in determining from what direction the impact occurs. If I am moving strictly vertically or horizontally I manage great detection. But when moving in both directions at the same time, strange things happen.

What is the best way to determine what direction a collision occurs between two rectangles?