I'm not 100% sure about your question, but I'll go ahead and answer. While obviously you're going to need the core/hybrid running at all times to have DHCP and the other functionality, you can shut down all the Media Directors (thin clients) and wake them up as needed via WOL (assuming your MD supports it). As far as NASs go, I don't think the WOL functionality has been extended to support those. I don't even know if most of those even support WOL. But if you are using a PC as a NAS, it might not work out of the box, but it sounds doable.
i am in fact using a PC as a server... i shouldn't say NAS because it's innacurate.
I am a current Media Portal user, but wish to try LMCE.. From within MP, i can select the server and click " WAKE UP ". This sends a WOL packet to the server.
I am looking at being able to do the same thing from within LMCE .
Currently, the server is running Windows Home Server, which i would like to keep. It's actually a decent piece of software.
Anyway, thanks for the help.. :-)