as far as i know it isnt a case of software, its the hardware. cd drives dont have the right 'equipment' to be able to read the extremly high density data on a dvd, nor can they change the focal length of their lasers to read the second layer on a dvd.
You cannot play a DVD on a normal CDROM drive. Fortunately, DVD drives are not too expensive and can either replace your CDROM or be alongside it. Just make sure your graphics and sound are up to the mark!
Thanks for the quick responses. And especially to you jj72 - made me laugh ("different piece of hardware known as a DVD player") - Yes I did think as much that it may require a DVD player. I do have one on my PC , I heard from the wife that the father in law was trying to convert his CD to play DVD's by downloading something but I didn't think it was as simple as that.