[CentOS] Migration from RH9

Hi,

	I will probably have to migrate a few servers running Red Hat 9 to 
CentOS and I'd like to have opinions.  One server to migrate is running 
Fedora core 4.

Reason for migrating to CentOS: no more security updates available, 
hardware change planned anyway.

Here are the services to be migrated:

sendmail
pop (not sure which daemon, I think it is running the default daemon in RH9)
DNS
apache+PHP website
FTP
Dansguardian
Samba
Perforce
Squid

I haven't seen any directories like LDAP or windows Active Directory, so 
I assume for now that all authentication is done locally.

Anyone has experience with that?  I'm not too scared about sendmail, 
Bind, apache/PHP (except that maybe the PHP upgrade may break the 
website, but this is easily managed and can be tested), ftp.

However, I don't know dansguardian much, but I guess it would be a good 
idea to integrate it with squid.

I don't know squid much, but depending on what they're doing with it, it 
should be fairly simple.

For samba, are there major changes between the default version in RH9 
and Centos4 or 5?

Anyone migrated a perforce environment?

I'm also wondering whether I migrate them to centos3, 4, or 5.  3 would 
be to make the transition easier, while still letting them have many 
years of security updates.

4 is the version I use most, I barely touched 5.

5 would be for xen and... your ideas?

I usually use OpenVZ for virtualization, but they might want to 
virtualize windows servers too, which OpenVZ can't do.

Any input would be appreciated,

Regards,

Ugo