golddeath,
My friend and i were hunting around for suitable cases for this exact same scenario and came across this case from Silverstone.
http://www.silverstonetek.com/products/p_contents.php?pno=sg03
In real terms to give you a rough idea of the size, the case is not much taller than his Creative 5.1 subwoofer and narrower! I was somewhat impressed, i even considered changing my Antec 900 for it, but then i'd miss the air-con for my room!
Silverstone actually recommend suitable PSU's on the website, however most standard 150 x 160 x 85mm ATX PSU's will fit. I would recommend one with short power leads, perhaps modular too as cable management within this case can be a little tricky.
The case will fit a standard micro-atx motherboard, as an example this one from gigabyte:
http://www.gigabyte.com.tw/Products/Motherboard/Products_Overview.aspx?ProductID=2775
I am not saying that is the best mb to go for, it's just to give you an indication of size, and the spec you can get on such a board.
The rest of the components you're pretty much free to pick yourself depending on budget and so on.
Jaffa