The difference between a fedora and a Centos /RHEL installation are not that big.. Fedora is on teh bleeding edge and Centos RHEL are the stable(!!) enterprise targeted distros. You have the same tools and command syntax as your fedora but are supported to be sound and stable for the coming years.
RHEL and Centos are being patched constantly but the newer releases of software (like samba) tend to be not included..
But if you have multiple servers you don't need to have both Scalix and Samba on one server. I would advise against it in heavier enviroments for Scalix can be I/O intensive..
But hey on a smaller system /enviroment you might need to so..
What i usually do is install a Centos box and install missing packages from RPMforge.
If you want state of the art stuff and install Scalix on the same server use an (additional) EPEL repo. BUT:
Scalix 11.4.6 is supported on the following platforms:
* Scalix Server: Red Hat Enterprise Linux 4/5, SUSE Linux Enterprise Server 91/10, CentOS 4/5, Fedora 9 and OpenSuSE 11.0. Supported architectures are i386 and x86_64.
Note: Fedora 9 and OpenSuSE 11 are supported for evaluation purposes and Community Edition use only; these are generally less suitable for production environments than their "enterprise" counterparts due to their frequent updates and short release cycles
Note: An unsupported Community Edition package for Debian-based Linux distributions is also available.
1) Scalix 11.4 will be the last release to support SUSE Linux Enterprise Server 9. It is recommended that you upgrade your server to SUSE Linux Enterprise Server 10.
taken from the releasenotes
http://downloads.scalix.com/rn/scalix-11.4.6-GA-releasenotes.html#mozTocId252172
Apparently it is a problem to support quickly changing platforms ..