Shuttle ST62K Zen – Quiet enough?

Hi,
I’m thinking of buying a Shuttle ST62K Zen. I want to use it in a living room. I have had a PC it the living room before, but when I was sitting chatting to friends with no TV or other sound on I could always hear the PC in the background.
The Zen would be sitting behind the TV so………….
1) Would I be able to hear the zen in a normal living room with the zen behind a tv?
2) What DB does the Zen run at (anyone know a website with figures) and what level DB can you hear things in a normal room (ie. Under 25 DB the human ear can’t hear it. Is that correct)

It would be great to have info from anyone who is running a Zen in their living room what their experience of the zen is.

Thanks in advance

Regards

Rapier503