This minitutorial will describe how to test if two vectors is collinear/parallel.
Checking if 2 Vectors is Collinear
Programming, by tedlindstrom.
Angle = ACos( Dot( NormalizedVector1, NormalizedVector2 ) )
.. This is how you check the angle between 2 vectors and if they are collinear(Facing the same direction). Note that the angle might not turn out to be 0 even if they are collinear. You should have a slight offset. How about less then 1.0?