Would you recommend a different CPU (if so which one?) or a different case?
Does the mobo have optical out for sound do you know?
I would recommend a bigger case TBH, if you think about the clearance from the top of the CPUs HSF to the case this needs to be reasonable, and as far as fans go, placement and size are important, the Antec Fusion has 2 120mm fans running very slow, keeps cool and practically silent. My Silverstone has 2 x 70mm, running slow but nowhere near as quiet, or cool, but has a much cooler CPU in that computer. If you are going to be watching films you dont want to noise of fans (the bigger the better, as you can run them slower but get better airflow) For a HTPC id always spend a little more, you can re-use if you upgrade and the last thing you want is a cheap echoy noisy case.
As far as the optical goes, you need to get the optional digital audio adapter/PCI slot thing that connects to one of the mobo headers, I already had one from an old PC I built. However I think the HDMI output carries sound if that is of any use?
Edit: like this one
http://www.glowtechnology.co.uk/product_info.php?cPath=5_79&products_id=72Bit expensive here though, could just buy a sound card with optical, or a different mobo
