There is a case at Directron.com that is supposed to be a huge heatsink that connects to the various hotspots in a computer through heatpipes. It costs 300 dollars, but I'm not sure it's in stock yet. I would go with karmasalad's recommendation though. Get a SLK3700AMB, then get the 400w Fortron Source PSU, go to bestbyte.net and get one of the 80mm NMB's for 1.99 + 1.00 shipping, and replace the fan in the Fortron Source PSU. Numerous quiet PSU's from Zalman/SilenX/others are based off of the 400w Fortron Source PSU. It has huge heatsinks. In addition, it can easily hold it's own in power and rail regulation against Antec's and Enermax's, while being a lot cheaper. The SLK3700AMB is bigger than the Sonata, making it easier to work in, but still offers the grommet mounted drives and the 120mm fan mounts. Coolcases.com offers a modded version where grommets are added to the fan mounts and the "restrictive" (restrictive compared to a wire grill, but not to most) stamped grills are removed and other nice stuff is done. NMB makes great fans that are used in servers where reliability is a must. These fans are top quality for a good price. I have heard that they make clicking noises at lower voltages, which you might encounter with the thermal regulation that the Fortron Source 400w PSU offers, so you might consider getting a Panaflo L1A, which goes for 4.99 at KD Computers (5.00 flat rate shipping) and 3.75 at case-mod.com (I have heard that case-mod.com might have gotten a bad batch or something like that). You could go completely passive on your PSU too by getting one of the ProSilence ones, but they carry a hefty premium. Seasonic recently came out with a 400w PSU that is supposed to be great as well. With an efficiency rating of around 75-76%, it gives off a lot less heat compared to other PSU's.
If you still want more, you might consider buying Melamine foam from McMaster-Carr for 2.95 a sheet. I've heard shipping is extremely reasonable. I remember someone mentioning around $5 shipping for four sheets. Each sheet is huge, 24" x 24". They provide a great value and are supposed to work better than stuff like Dynamat or Akasa Paxmate. Acoustimat (sp?) is also a possibility, but it is much more expensive. It's available at SiliconAcoustics.com. I'm not sure how the Melamine foam does against the acoustimat stuff.