[CentOS] Dovecot problems

Actually, I'm having problems with pop and imap.

I changed mailservers this weekend, going from a Centos 3 box to a 
Centos 6 box. The Centos 3 box used the old standard imap and pop 
servers. We use horde for our webmail. The pop3 mailboxes (mbox)  were 
in /var/spool/mail and the imap folders were in /home/user/mail, which 
horde took care of.

Upon starting the Centos 6 box, I ran into tons of login and viewing 
problems. I tried Cyrus for imap, could log in, but couldn't see mail in 
the imap folders. Using dovecot for pop, I eventually could get logged 
in, but kept getting the "couldn't open INBOX" message, so no one could 
download their email, even though sendmail was delivering it properly.

So here's my question:

Can (should) dovecot be used for both imap and pop when considering the 
above setup of mbox in /var/spool/mail and imap folders in ~/mail? Horde 
will read the mbox to display new messages in it's screens.

If so, does anyone have a pretty good link to how to make dovecot 
function using the old Centos pop/imap scheme? Should I try and convert 
the old mbox files to another format or destination to make this work?

Thanks for any help. It's been a long night, going on about 14 hours now 
and I'm just getting the old server back to current until I figure this out.

steve campbell