I don't want to need to learn Unix to set this mail server up. However, once I do get it set up, then I know I will play and learn. But I don't want a steep learning curve just to get this setup and running.
Fedora http://fedora.redhat.com/
or
Debian http://www.debian.org/
Redhat is easy to make cd ISOs and install. But, they're all the same when you really get down to it anyway. I've just been stuck on redhat since day 1 so I've only played with other distros for fun. The most important part is to get apt-get or yum (http://apt.freshrpms.net). Don't bother to manage packages any other way.
You're definitely going to "need to learn Unix", though.
