I'm not gonna bother scrambling every detail about this, but here's the short version.
I wanted to make a fairly low power and reasonably powerful gaming machine some time ago. Had to be able to play Skyrim.
I took the easy route by buying an Antec NSK 3480 case and just modded it to fit to my purpose.
Drilled some holes for cables and the fan on the bottom, put extra case feet to get more airflow and replaced the front of the case. I put the power button on the top for easy access. There's also a fan controller in the back next to the PSU.
Painting the case from inside was just something I always wanted to try.
Here's the result in one big picture:
I know, it looks like some design product from the 80's.
Parts: Some Asrock mobo, 4GB Kingston ram, i3 2100 undervolted w/ AC Freezer13 pro, Asus HD6850 w/ Accelero S1, Intel 120gb ssd.
Draws about 37W idle and just over 100W on load if I remember correctly. (I might not)
Stays cool and quiet and can run Skyrim at almost full. Mission accomplished.