I came across this site (http://www.afrotechmods.com) the other day when I was looking on Google for a way to reduce the amount of dust (and other insects – yes, I had a dead moth in my PC!) from getting into my PC.
I have to say, this is one cool site (for people who are interested in computer hardware anyway) that have loads of things in it that’ll keep you reading for at least a couple of hours. You really need to look at it yourself to see what I mean.
(Oh, and as for my search for a dust filter, I found this page, but I haven’t tried it yet – It looks promising but I’ll need to make sure the airflow through the paper is good first of all – I really don’t want to fry my CPU…)