I just took a shop vac and blew the dust out of my PC.  It was the first time ever doing it since I built this PC over a year ago.  I clean out my PC regularly with duster and my vacuum cleaner, but I wanted a very clean cleaning, so I rented a shop vac from Lowe's.
The dust was unbelievable.  I'm going to have to clean out my living room now.  I held my regular vacuum cleaner's hose up so that it would collect the dust, but the red light came on because the filter got clogged.  My god...