Cool, quiet and small in a standard ATX case is a tough proposition. Check out the SLK1600 and SLK2600 boxes from
www.antec-inc.com. They're widely available thru a variety of Vendors. It's very difficult to get any smaller w/o serious compromise on the cooling side- boxes with side-saddle psu's generally don't cool worth a damn... neither do boxes w/o good rear fan mounts and open intake areas....
I have not personally used these, but they would seem to follow along the lines of the SX family of cases, some of the best in terms of cooling and overall features. Big, though....
The standard smartpower psu's are good quality, have temp controlled fans, not as quiet as the Trupower psu's.... not very loud, either.
Matx boards lack only the overclocking bios tweaks and a couple of slots present in their big brothers. They generally compensate with onboard ethernet and sound, some of which is quite good. It just depends on what you want to do- compromise is inevitable, one way or the other.....