While I had my PC’s guts hanging out anyway, I decided to go ahead with yet Quiet PC modification: a silent video card heatsink. I have an ATI Radeon 7200, which comes with an on-board heatsink and fan. The new heatsink is a huge thing of copper and aluminium that replaces both of these. Without a fan, it is obviously going to be quieter than the old cooling solution.
I had thought my PC was quiet before…. Wow.