My poor media server!  I stuffed my old PC, with its miles of cords and wires, behind the television a year ago.  My intention was to figure out some sort of shelving for it.  It streams my Netflix, Hulu, and Pandora.  It also acts as the file server for my home network.
The machine was often working too hard.  The fan would kick in quickly if I gave it a CPU intensive task.  I figured the computer was probably dusty inside.  As it's sitting directly on the carpet, fuzz and lint gets sucked into the machine through the power-supply fan.  I opened it up and gave it a good cleaning.  A blow-drier which never gets to work on hair, came in handy.  The housing around the CPU was packed with dust.  
It's now running much cooler (and more quietly).  It's ready for hours of instant streaming, DVD copying, and assorted networked media tasks.