What is the best Linux Distribution?

It's all in personal preference. SOLDIERX officially supports GNU Debian Linux. Please see http://www.debian.org for more information.

There is a good guide on choosing a distribution located at http://www.desktoplinux.com/articles/AT3269115798.html

If you are looking to learn Linux, Amp suggests trying out a Live CD distro. He personally recommends Kubuntu (The KDE derivative of Ubuntu) to newer users who are looking for something to use to learn the basics of operating within a Linux environment.