Depending on the components you have, you might be able to run without
any intake fans at all. :Q
I know this doesn't get talked about a lot 'round here, but the irrefutable fact is that there are gazillions of computers all over the world that run just fine with no intake fans. (And not just Cerelon rigs.) Now, would it be a good idea to run an overclocked, cutting edge P4 rig, with a high end vid card or SCSI HD, for example, that way? Perhaps not, but the truth is that most rigs will likely run just fine.
Front intake of "cool" air (which it seldom is) is vastly overrated IMHO. And I've read a number of test reports over the last couple of years in which the author/reviewer comments that front intake fans only impacted temps slightly, if at all. Side intake fans near the CPU can have a bit more effect, but then the dust intake is also heading right towards the CPU and heatsink.

If you have an
efficient exhaust scheme in your case, and a truly high quality CPU heatsink & fan, simply exiting the hot air out quickly will enable most computers to run just fine. The computer will not melt, it will not explode, it will not crash or BSOD, you will not be contributing to global warming, and the world will keep turning.
For anyone who wants to challenge me on this, simply think about how many people report their temps plummeting simply by taking a side panel off. Doing so does NOT pull more air into the case, does it?

It increases hot air evacuation, and WHAM -- down go the temps. :thumbsup:
GY's broken link to what I assume was a room air purifier (?) is an idea I highly recommend. I use an air purifier in my office and it really makes a difference in the amount of dust circulating around. Less ambient dust means less dust that can find its way into your computer in the first place (duh!

).
With your dusty environment, I'd concentrate on getting a reasonably airtight case and creating a
really efficient exhaust system. And like JBDan said, you can make any case virtually dust free by sealing off areas/holes with tape or silicone sealer or something. I really like Cooler Master WaveMaster and Praetorian cases, even though they are not perfect in all areas. I'm mentioning them 'cuz you said you like aluminum cases. I also like Antec's new P-150 even though it's not the most fancy looking case out there.
Interesting user name, BTW. You a Zep fan?
