Diagnostic Software recommendations for newbies

I am looking for recommendations for diagnostic software. I do not know where to begin, what might be needed or how to evaluate it.

I am a commercial photographer and would like to ensure 100% my images are in good shape on CD or DVD before final delivery to my end clients.

Any help is greatly appreciated

“Diagnostic software” is for when you know you have a problem.

If you want to avoid sending out problematic discs in the first place, then the program to use is CD-DVD Speed.