This sounds rather familiar. I have a similar post somewhere further down the forum when I was considering the Sonata II for my new system.
If it isn't too late to suggest it, I went with the Antec Solo case in the end which is similar design to the Sonata II if you like that (including the fact that it's quiet). You'll want to couple it with a quiet PSU too - I went with the Antec NeoHE 500W, though you may be OK with a lower wattage version on your system, I don't know. :-) (I think the next model down is 430W)