Hi Zimbra Sales Support

We are using the free Zimbra 4.5 edition now on Fedora 4, and plan to upgrade to the commercial Network edition. But there are a couple of problems:

1) There is no Zimbra 4.5 Network edition binaries for Fedora. There is Zimbra 4.5 Network edition binaries for Redhat Enterprise Linux 5 (REHL 5) Can we use Centos 5 instead of REHL 5?

2) I know it is possible to run the Zimbra 4.5 Network Edition's setup.sh and it will just upgrade the existing free Zimbra 4.5 free edition to network edition. But to do this, we have to upgrade our OS from Fedora 4 to Centos 5 (assuming it can be used in place of REHL 5) and that is not acceptable as it will be too disruptive. Can Zimbra 4.5 Network Edition binaries for REHL5 be installed on Fedora4 to upgrade the existing free Zimbra 4.5?
If this is not possible, We would have to get a new machine and install Centos 5 and Zimbra 4.5 Network edition on it, rather than upgrade our live server to Zimbra network edition. (this will be costly!) Question is how do we transfer all the accounts and mails from our live server to the new server?

Thank you.