Nice choice raldo! I also have asrock 330, and, in general, very satisfied - its powerful silent htpc.
little of my experience:
I use it as library client.
Win7 x32 installed, no AV scanner (I tried NOD32 version 4 - but it is very slow loading database (3-5min for 8 MB MC database), and I failed to add it to the NOD exceptions). I have Gbite lan and have some weird problems with nvidia driver for this.
Small disadvantage of productivity GPU can be felt in the theater mode, but at a moderate 3D settings can achieve exactly smooth.
I had to abandon the heavy cover (1-2 MB) for my files, because their presence strongly inhibited switching of MC views on Atom machine.
Switching standard views of MC is a major CPU load and appreciable delay - here we could benefit from a more powerful CPU or a more optimized code MC. In favor of the latter, I note that switching views on a powerful MC server also does with a perceptible delay and the "white screen" of frozen application, with the little CPU loads.
Syncing library with a server in my case takes 2 minutes and completely loads one core of an atom. I do it on average once a day, and the main problem for me here is not the expectation, but reset the current "playnow" after updating database from the server.
Formerly MC continually crashes after waking up PC from hibernate mode - due to the use of MC, I had to abandon the energy-saving technology. However, in recent versions of M15 it does not happen - thanks to our developers, probably this is due to recent changes in the library server.
My friend also uses ASR330 as a HTPC, but in the local base mode. He expanded memory up to 4GB, set Win7 x64 and also has a positive emotion from the system. He does not complain about delays and hang - but the size of the base we have is very different (8TB in my case, and 200GB my friend)
ION works fine with standalone MPC video decoder (DXVA), M$ VC-1 decoder (also DXVA I think), CoreAVC (CUDA).
...setting up a Library server on the office pc and connect to it from the ION
I think this is the best choice)