[CentOS] minimize download bandwidth techniques

I know of a few techniques for minimizing server bandwidth when bittorent is not an option.

1) If you have the beta isos, you can rename them as centos 5 isos and then rsync from a mirror that allows rsync (such as kernel.org). Then only changes from beta to centos 5 plus some overhead is downloaded. I suppose you could use this technique with bittorrent too.

2) Instead of downloading both cd and dvd isos, just download the cd isos and use a script to create the dvd iso. You can rsync like step 1 if the dvd md5sum differs.

A cd to dvd script is at url below (although I haven't tried it yet). http://www.tuxforums.org/forum/viewtopic.php?t=446