After being an original modder of xbox's and running XBMC, then moving on to a popcorn hour (to stream blurays) - and now a dual computer build starting with the latest XBMC is on order - there is nothing like a good powerful EXTERNAL device that can take care of all your needs...
I honestly would never buy a receiver for a network GUI as IMO they are all just crap...
I stream all my movies & music through my PCH's right now(which will be sold soon), as nice as they are, I will do the same with my new HTPC's... After seeing what krzywica had running with his XBMC computer rigs - I new a change would be in order - so freakin incredible.
Seriously check out some of these skins to use as GUI's
http://xbmc.org/skins/
Full network control with an android app on a tablet or phone...