There is no easy way to keep the dust out of a modern computer. The use of positive air pressure works, but on cases with open mesh the amount of fans needed can be noisy and expensive. It is just better to adopt a good cleaning regiment for your system.There is nothing wrong with vacuuming your computer, as long as you do it with the power off, and use the proper attachments. Try to avoid the use of compressed air, the stuff can cause more harm than good.If you have some dust impacted into heatsink fins then use the compressed air, but do so away from the MB.