We are running Zimbra (ZCS) 4.5.11 on CentOS 4.3 (RHEL 4.3). We'd ultimately like to end up on version 6.0. We pay for support, but understand that we can't use it as CentOS isn't a supported platform. Since loosing our Linux Sys Admin, we feel support is a safety net we can no longer be without.
What would the forum members recommend as the most painless path to end up on a supported version 6?