Very doubtful that it's quiet. The spec sheet itself cites "Idle mode: 31dB
" -- which we have to assume is 31 dBA/1m -- above our minimum standard for "not noisy" -- ie, 30 dBA/1m or less.
I'd suggest other answers, but it's not clear what your question is. Give us the role you want your PC to play and we can make suggestions.
In general, in the UK, there are a handful or quiet PC makers --
Tranquil PC -- http://www.tranquilpc.co.uk/
PaQ -- http://www.paqt.co.uk/index.html
others.... check the UK sticky in Deals, Vendors and Classifieds