Hai,

If you are new with Linux. You should know by now, linux has numbers of distrobutions to choose from. This include big name like Red Hat, Debian, Ubuntu, Suse, Mandriva and others. All information about Linux Distribution can be view at http://www.distrowatch.com/

Most of the Distro can be used as workstation but to select which distro suitable for running email server, web server and others can be confusing.

Fedora is more up tp date with package contain latest version of the software. This can be a risk because new version is stable but not fully tested in production enviroment.

Red Hat Enterprise is the right but we need to pay to download the update.

Centos may be the right choice for enterprise. visit http://www.centos.org/ for more information how Centos can help you to build a stable Linux server for your enviroment.