I'm in a similar situation, I was going to make a seperate post but might as well add to this!
I have Intel NUC i5 and tried to run Plex server and Plex home theatre on it, but the performance is awful when playing mkv files. So a NAS that can act as a Plex server instead would be ideal. I think thats what the OP wants too, a NAS which can do the Plex server side.
So I am also looking for a NAS to do this, but not crazy expensive if possible!
Just stick OpenELEC onto the NUC. Have the files on a shared PC, attached to the NUC usb or on a NAS and all will stream with no issues. Sorry, havent really used Plex much apart from sticking it on my dads PC to stream to Roku box.

Thanks for the advice, but I really want to run Windows on the NUC as I use it for simple games, browsing the web, etc![]()
also the poor performance mentioned when playing MKVs can be overcome by telling PLEX to just do "direct play" rather than directplay/transcode
