Just some words about my experience moving my data between CentOS 3.4 and Debian 3.1. For the most part it worked well. I backed up my data on the CentOS server with psadump, then moved the data to the Debian server for a psarestore. I created the ipmap and shellmap files and the restore went smoothly. Only 3 things went wrong: 1) Spamassassin went screwy, it applied itself to mail accounts which I told it not to. Had to run mchk to fix it up. 2) SSL certificates got did not come across smoothly. Needed to reupload all certificates. 3) psadump missed 2 directories for some reason. Other than that it went extremely well.