IMy system is a 3.06ghz p4 with a AIW 9800 pro
The case is a lian li pc6070B and it is really cramped inside because I have 4 HDs 2 optical drives, a floppy and a card reader.
My cabling is laid out very neatly with nearly everything hidden under the motherboard. However the airflow sucks so bad with this case, my temps were around 44-47 idle.
After some more cable arranging, adding a weak peltier cooler (from thermaltake), and a 92mm hole to the side panel, my case is finally very quiet with idle temps at around 30c with and full load at 45-47c, but always under 50c.
I have a papst fan on my sidepanel intake. 2 NMB 80mm fans for front intake, a weird thermaltake led 80mm fan for exaust (it came with the peltier set), and of course the zalman 400w psu is the final exaust fan.
I have no filter for the side panel, but I open the case up often enough that I have opportunity to clean out any dust build up.