Originally Posted by Chozart
What pook meant is to create a system that has a slight over pressure. Thus, the intake (front) fan should be more powerful than the exhaust (back) fan. Or, two intakes, and only one exhaust. That way, the intake fans pull more air in than the exhaust takes out, and there is a slight overpressure in the case. That way, air is not 'sucked in' from other openings in the case, and dust accumulation is minimized.
Then you get into the whole debate on whether a negative or positive pressure is best...different debate for a different thread I know but I tend to go with a negative pressure and deal with the dust by cleaing out my case once a month.
My ghetto trick to keep dust out?
Bounce sheets. Thin enough to let air through but will keep out most of the dust and give your computer case a nice, light, springtime scent.
Oh, and they help control static.
In all honestly you can get any type dust filter, cut it to size and put it in between the case and your fan. Instant goodness.