md5sum of a cd

["Jim B" <vader@stargate.kersur.net>]

I just burned some CDs from their ISO images.  I have the m5dsums of the
images, and now I'd like to compare a hash of the completed CD against the
original image... basically I want to make sure the CD was burned ok.

I'm concerned because the hard drive I downloaded the ISOs to was bad, and I
had a hard time getting one of the images off of the disk (kept getting read
failures).  I burned 3 of the 4 anyway, and I haven't burned this last one
yet.  I'd like to verify that the others are all right before I waste
another cd, just in case the others are trash.

I tried md5sum /dev/hdd (which is my cdrom drive) but I would get an i/o
error after a few mins of chugging.  I don't know if I'm doing something
wrong, or if the disc is bad, or if there is a better way for me to check
these discs.

Thanks.