Over the past few weeks, the fan noises have been nagging at me. Even when just going into Pale Moon, I'd hear something spooling up inside, and finally I recalled that when I got this machine it was never this loud, even with WoW going full blast. This led me to twig to the realization that something is probably clogged with fuzz.
So today I shut 'er down and pulled 'er out from under the desk, and yanked the cover, and--sure enough--there was a lot of lint clogging the heat sinks. The big vent grille on the side was choked with it. The exhaust fan was clogged. The heat sinks for the processor and on the video card had neat circles of lint around the edges of the fans.
Took a can of compressed hydroflurocarbon, blew all that crap out. Then I got Mrs. Fungus' machine (a scant three months newer) and blew it out, though her machine wasn't as bad off since it's higher off the floor than mine is.
Done with that, I fired up Floristica, went into WoW...and she's utterly silent again. That'll do.