At the risk of flogging a very dead horse, heres a list of the changes made to the dvds, its quite an interesting read.
http://www.dvdanswers.com/index.php?r=0&s=8&n=1&k=star+wars&c=28 SW
http://www.dvdanswers.com/index.php?r=0&s=8&n=1&k=star+wars&c=29 ESB
http://www.dvdanswers.com/index.php?r=0&s=8&n=1&k=star+wars&c=30 ROTJ
http://www.dvdanswers.com/index.php?r=0&s=8&n=1&k=star+wars&c=28 SW
http://www.dvdanswers.com/index.php?r=0&s=8&n=1&k=star+wars&c=29 ESB
http://www.dvdanswers.com/index.php?r=0&s=8&n=1&k=star+wars&c=30 ROTJ