In today's Sony Vegas Zen Tips #14, I show how to pull apart a computer and clean all the dust out of it.
It is important to regularly clean the dust out of your computer, otherwise it may overheat when the CPU is working at maximum load. Rendering video or playing a game at maximum settings, are two of the most stressful things your computer can experience, because the CPU is running close to 100% capacity and creating a lot of heat in the process. If the CPU cooler is caked in dust, it won't be able to cool the CPU properly and may overheat.
I recommend a full detailed clean once a year, exactly like I showed in the video.