This little machine sits under my TV and is fully automated to download movies and TV shows. Everything can be remotely controlled from WAN using ddns, including allowing for VPN login.
The box's primary function is to download shows and movies, sort them, and then play them back through XBMC. I use some streaming as well. The secondary function is to play games which run on my primary PC and are streamed through Steam's In-Home Streaming. As such, having gigabit ethernet was a must-have on the motherboard, and a little bit of graphics oomph to decompress the 1080p video stream.
This is a wonderful little machine. I did everything I could to keep the power consumption to a minimum, which allows the high-efficiency fans to barely run. When this machine starts up, the only sound is that of the hard drive spooling. Under load, certainly whatever little sound gets made it drowned out by whatever movie or game is being played at the time. 300W is in fact overkill, as the peak draw should be closer to 150W. On the plus-side, this gives me a bit of headroom to add a graphics card if I decide, so that the box can play games without taking over my main PC at the same time.
In terms of the build, almost everything was simple. The only issue was with installing the noctua fans with their silent tool-less mounts. The silicone inserts in the bottom corner were just about impossible to pull through; on one, I used a pair of tweezers to grab and pull, and another I cut short so that I'd be able to just push it in (see photos). Cable routing was a bit tricky, as the PSU is non-modular. It was a bit of a trick to find a place to shove all the molex connections, none of which I used.
The case is amazing, and I can't recommend it enough. It allows for a micro-ATX build, which allows for a whole lot of cost savings and build flexibility over an ITX build. The top vent is directly above the CPU cooler, so air gets blown directly out the top of the case. The dimmer on the front LED is icing on the cake, but is actually fairly crucial to ensuring that there isn't any glaring bright light while watching a movie in a dark room.