Beh, some people claim that because of Unity's search features. I'm not a fan of Ubu, but some claims are just stupid.
If you're going to use CentOS and firm about it, check if Zentyal is a live distribution. Run it. Find out what software it uses (a simple dpkg -l | grep ^ii should be sufficient to give you that list), then install that on your CentOS system - just find the same software in CentOS' repositories. You're going to have to configure stuff, but if you're set on not using Zentyal as-is, it's going to be a bit of work for you.