The easiest way to validate a set of DH parameters is to plug them directly into a simulator which can build a robot model from a DH table. Once you've got the DH-generated robot model, you can verify that the robotic structure that is generated is what you would expect based on your DH table.
The most common DH-table based robot simulation package that I've worked with is the Robotics Toolbox for MATLAB written by Peter Corke: http://petercorke.com/wordpress/toolboxes/robotics-toolbox.
I'm not a fan of DH parameters but they are entrenched in robot kinematics. An approach I prefer is to just write the whole chain as a series of simple transformations, eg. Ry is a rotation about the y-axis, Tz is a translation along the z-axis. From your figure, starting at the base and applying the transformations consecutively, you could write it like
but I get lost with what happens near the wrist in your diagram. The Robotics Toolbox has a function, DHFactor, that will take a string like this and automatically compute it to DH parameters.