Thanks everyone. Shooting tethered made a huge difference from my previous attempts.
I've got a semi-fancy faucet, so I was having a hard time getting consistently well focused shots before. I was trying 2 different approaches, focusing on a steady stream, which worked well, but then drips were not quite in the same focus plane. I also had tried focusing on the front rim of the glass, then the back rim, and finally splitting the difference.
As much as I love my 20D, trying to use the micro LCD to check my focus was not working out well, so I decided to try shooting tethered for the first time ever. It took me longer to find and install the canon utilities than it did to get the setup. As for setting the focus on the drops, it took maybe 3 or 4 shots to tweak the focus to the results shown above, and then I was good to shoot. That left the timing as the only challenge. I took about half the shots with all the lights in the room off, just listening for the drip and manually tripping the shutter release.
Next time I want to try limiting the light some more with some home-made gobos.
