Spent the evening (after dinner) quieting my Athlon64-based Windows game machine. Installed three silicone fan gaskets, one power supply gasket, organized and cable-tied all inside wires, and for the biggest effect, installed a variable-voltage fan control for the big 120mm fan in the front of the case. A knob protrudes out through a slot cover on the back of the machine that I can use to adjust the voltage (and therefore the speed) of the fan. Turning the knob down 3/4ths of the way gets rid of the harmonic that was responsible for most of the noise I had been hearing yet maintains adequate cooling.
I also just got through installing an InvisibleSHIELD screen shield for my 30G Video iPod. If I like the end result, I’ll pick up their version for the Motorola SLVR phone too, as my phone gets a lot more “pocket abuse” than the iPod does.