Step 1: Parts Needed
a $5-$10 80mm or bigger case/CPU fan (I used a 92mm cooler master CPU fan)
a dremel with a with a metal grinding disk or any similar tool
a spare 3 or 4 pin fan spot on your mother board *note: 4 pin fans work on 3 pin spots*
$1 garbage bag ties
***If your case does not have holes or some ventilation in front of the CPU fan area you might have to cut a hole and put some mesh or something there***
**If you don't have a spare 3 or 4 pin can spot you can spend an extra 10 dollars to get a fan like this one Arctic Cooling Arctic F9 PWM 92mm case fan**
Step 2: Cutting
If you already have holes or vents in front of your CPU fan then you don't need to cut a hole there but if that is not the case then you need to cut a hole in your case and put mesh there.
I already had ventilation so I only had to cut in a little hole for the wire. also make sure that the hole is big enough for the plug to fit through
Step 3: Mounting the Fan
Make sure that when you put the tie into the mesh or venelation on your case that each end of the tie go in different holes.
Step 4: Finished Product
this simple case mod brought my idle CPU temp from 43 to 40 and my average usage temp (Firefox 4 beta, ATI Catalyst, spybot with teatimer, zone alarm, bitcomet, netgear tool, avast and tuneup 2010)