A desktop PC is an efficient dust magnet, and you should definitely look into cleaning your computer's fans and internals from time to time. Yes, even in your nice, clean home. The main reason is that heat is the enemy of electronic components, and by keeping fans and the like clean you allow the computer to work more efficiently and to probably last longer. I'm not suggesting you use the vacuum cleaner hose attachment, though - that's NOT a good idea, because of the potential for a lot of static buildup during the process (another enemy of electronic components).
HowToGeek has a detailed guide on how to take care of business, though.
|You know it's not supposed to look like that, right?|