The best website for quiet pc info is
www.silentpcreview.com
As far as quieting the fans, I have found the Panasonic Panaflo fans to be the best combination of price, low noise and good airflow. They are available from Newegg and Directron. A good heavy case with thicker panels helps. I have heard that Brown Bread from
www.b-quiet.com is a more effective, lower cost alternative to Dynamat, but I haven't tried it. Silent PC Review has all the info you'll need to quiet that PC though.