If you do not feel like using Solaris or OpenSolaris, the Linux distributions Debian, Ubuntu, Mint are worth trying. However, be warned, if you're looking for 64-bit support, last time I tried it on Debian, I struggled and finally abandonned.
This section explains how to configure your system's services locale, paths, network and main applications such as mail, SSH, NFS. It also explains how to use/create/work with Debian packages and which are the most interesting ones to have. Finally, it provides a few notes for typical Debian applications.