I am almost a total nubie to Linux and I downloaded Redhat 8.0 at work to get a cheap mailserver for the office. We were using an OLD Mac with their mailserver software which couldn't be configured as anything but an open relay!!! Needless to say, suddenly it was locked up one day. We rebuilt it and "released the hounds" and discovered that we were spam central! Redhat to the rescue! We installed it on a spare intel box we had semi-retired. Sendmail can be configured properly so you have complete control of relaying.
In order to become more familiar with it (Redhat), I built a modest box out of parts I had laying around (which included a GeForce2 MX 400 based videocard) and voila, a nifty second box in my dungeon at home! KDE and Gnome can be configured many ways and look great. But, if you can't stand the command line, buy M$ XP instead. I have it on my other box with Windows 2000 (which I love).