I have an INWIN full tower case I have modded for function, not looks since it sets under my desk. Nobody could see inside it anyway. One thing I have not seen some air cooling modders do is one thing I did do...I cut a hole in the motherboard slide out tray where the backside of the processor and integrated northbridge/southbridge chips are and have an Enermax 80MM adjustable fan mounted on the right side cover blowing outside air on the back of the MB to help cool that area. I'm not saying it would help everybody, but it cooled those items down 4 F with the fan adjusted to its lowest speed.
Here are a few sites for silent system building. That is my next prodject.
http://www.ultraspec.us/pegasos.htm
Check out the silent fan and PS links, but you may also find that Morph OS system interesting to read about on the home page.
http://www.nexustek.us/
That will give more info on the Nexus brand of stuff.
Last one:
http://www.endpcnoise.com/
More Nexus stuff. Check out the copper lined hard drive silencer. It is pricey, but it is the only one I know of you can put a 10,000 RPM drive in, quiet it and it cool the drive and with NO FANS to add noise. A friend has a couple and swears by them for his 10,000 RPM SCSI drives. He says they cooled better than any fans he'd ever put on them. He does have an 80MM Nexus 17.6 dba fan blowing across the silent HD cases for extra cooling, but said he doesn't need it. The hole was there already from a past mod, so he put a fan quiet there.
With just air cooling and no screaming fans (all Enermax adjustable at low speed) and a stock AMD heat sink and fan my system will max out at 102 F (38.8 C) under heavy load drop down to 92 F (33.3 C) under light load. I have 12 fans counting them all, 4 40 mm being on the two hard drive coolers and I want to reduce the number and get as good or better cooling at the same time cutting down the noise. The case has sound absorbing material I applied.
The PS I want to mod and put a single 120MM silent fan on it, get rid of the two 80MM fans that together can't move the same CFM of air the single 120MM can and can't do it as quietly. The other stuff is get rid of the HD cooling fans using those copper lined inclosures and replace the case fans with the quieter Nexus fans. Maybe do the heat pipe cooler on the vid card and last finally replace the stoch heat sink on the processor with the Nexus AXP 3200.
Sounds like a lot, but it will all work on my future system I want to build.