Linux, Unix, Windows OS Options
Linux (CentOS/Ubuntu/Debian/etc) or BSD (FreeBSD): FREE
CloudLinux: +$12 / mo
Windows 2012 Essentials: +$12 / mo
Windows 2012 Standard Edition: +$18 / mo
Windows 2003/2008 (64bit or 32bit) Enterprise: +$35 / mo
Windows 2003/2008 (64bit or 32bit) Standard: +$18 / mo
Windows 2008 Web Server (64bit or 32bit): +$10 / mo
Windows 2003 (64bit or 32bit) Web Edition: +$10 / mo