Well that made a huge difference.
My Ubuntu server was originally installed onto an old 80Gb Maxtor drive, and it had a very very loud, horrible, whiney, grating, pulsing sound. Since I've recently freed up some drives from my old PC, I went looking for a way to replace the old whiney drive with a newer 200Gb Maxtor SATA drive that was just sitting in a drawer. This 200Gb drive may not be ultra fast, but it is quiet and still faster than the old drive.
So I found this useful link on how to clone my Ubuntu boot disk onto the new disk. I used SystemRescueCD to do it all and everything went according to plan.
The noise in the office has dropped considerably - it's sooo much more comfortable in here now. Ahhhh.