Postgraduate studies or Diploma?

Which course should I study for?

The Postgraduate Certificate in Human Resources Management with the Open University

http://www3.open.ac.uk/study/postgraduate/qualification/c82.htm

OR

OCN Human Resources Diploma

http://www.openstudycollege.com/courses/ocn-human-resources-course.html

Which one is better to study in your opinion? I already have a degree in business studies and French.

Dimploma