[Alug] Checking the integrity of a CD

Hi, I have recently obtained a set of CDs from a friend and would like to check their integrity against the md5 ISO checksum I have obtained from the original supplier in order to reassure myself that no errors were introduced during the burning process. Is it possible to directly check the md5 checksum of a ready made CD or do I need to use CD burner software to create an ISO image of it first and then checksum that? Ian.