I stopped using toothpaste about a year ago, to no perceptible effect. Brushing+flossing alone is sufficient to keep your teeth healthy.
Lots of tests have been done, here's a good one:
Running under DOS typically does not give you 100% control over the CPU:
Maintaining contrast with the adverts was the only reason networks didn't remove all the dynamic range from the programming. Now that the contrast is illegal, there's nothing stopping channel vs. channel competition for loudness. Just as election campaigns target the swing voters, TV producers care about the channel flippers, and being louder than the competition is an easy way to grab their attention.
This law has the perverse consequence of making *everything* sound as bad as the adverts.
I also change my sitting position frequently. I removed my chair's arm rests to allow more flexibility.
I use a Microsoft Natural Ergonomic 4000, which has a great layout but poor quality rubber dome keyswitches. Several people on the geekhack.org keyboard forums have modded these to use mechanical keyswitches, so maybe I'll do the same.
Do you use a wireless mouse? Some of them update only at about 60Hz, so you'll not see the benefit in window dragging. And even with a wired mouse, the default 100Hz (Linux) or 125Hz (Windows) mouse update rate isn't fast enough to guarantee updating every frame on a 120Hz monitor, so you'll need to change mousepoll (Linux) or install a hacked hidusbf with test certificate (Windows). It's also possible your window compositing system is capped at 60fps. IIRC correctly Compiz does that unless you change some hidden setting, and maybe Aero does too. I don't use compositing.
The difference between 60Hz and 120Hz is extremely obvious if you're actually updating every frame. I refused to use a LCD until 120Hz LCDs were available, and even that's just barely adequate. A 200Hz CRT is clearly smoother.