a couple of things that really helped me when converting from mbox to maildir. First is to see how simple procmail changes could be. in your /etc/procmailrc file, just add the following.
MAILDIR=$HOME/Maildir/ # Make sure this directory exists! DEFAULT=$MAILDIR
if you're using per user procmail files, the exact same two lines will also work to ensure proper delivery.
if you're anything like me with 200 plus mailboxes, the following utility is really superb at doing the conversion all at once. Granted, I had to wait awhile to convert the GB+ of e-mail but I had other things to do and not getting interrupted every few minutes made the time reasonably productive. :-)
http://batleth.sapienti-sat.org/projects/mb2md/
I was getting an error about some sort of illegal character sequence but the mail seems to have converted fine.
I think the next thing to do is create a new partition for home and make it ReiserFS.
---eric
-- Speech recognition in use. Incorrect endings, words, and case is closer than it appears