The MD5 helps ensure a good download. Even so, some burners, historically have been a little flakey when allowed to choose their own burn speed, even with buffer underrun protection. I have occasionally had to set the recording speed to numbers like 4 or 6 to achieve a good burn. There is an md5sum file in KNOPPIX which you can use with an md5summer to check the quality of the CD if you have doubts about it. The file has the md5sums for all of the files on the CD.