I'm using Kodi, (Previously XBMC) running on the Openelec platform on my main system. Have it installed on an Intel Nuc. http://www.intel.com/content/www/us/en/nuc/nuc-kit-dc3217iye.html and very happy with it.
You could also run it on a Raspberry Pi (B).
The Nuc is a bit expensive, but I...