you do not need a gui at all. however, i dont recomend using vector for your server. In fact i would go with ubuntu. The reason why is because of apt-get. You will beable to install 1000s of programs, security patches and updates at the blink of an eye. It has an easy installer that walks you through everything and you can find tons of support in there wiki/forum.
If your interested in setting up an ubuntu server you can check out this little how-to i made at Ubuntu Basic Server Set-up