Yep 1080p over Samba Windows share works fine (that's what I do).

Not tried full BluRay rips as I don't have any.

You have my interest. Now I need to figure out what and how to do with one...

edit: or buy a NUC instead.

This thread - http://forum.xbmc.org/showthread.php?tid=194362
This wiki - http://wiki.xbmc.org/index.php?title=ASUS_Chromebox#Device_Preparation
(ASUS and HP are basically the same)

You need to do the device prep first.

I only did 1.1 and 1.2 of the device prep because I've gone for standalone OpenELEC.

You may see a few posts near the end of that thread from me. The fan can get a little noisy but I think that's because I'm doing some HQ Deinterlacing and scaling which is quite CPU heavy. For standard 1080p playback it should be quiet/silent, all done by the Intel HD graphics with ease.

Remember you'll need a remote, phone app or some sort of thing to control it (keyboard+mouse bleurgh)

Or an NUC. If money isn't an issue then an i3 NUC is nice.