Ok, I don’t really need my own entry to tell you that MacOS 10.3 (a.k.a. “Panther”) rocks. However, it can be a bit bigger than you want because it has so many silly languages installed. Frankly, the average person, even a non-American, probably only has use for a handful of languages at most. MacOS X supports dozens. There’s a cool program that uninstalls the superfluous resources that provide support for languages that you don’t use.
I’ve also gotten some good mileage from Monolingual. It helps remove the bazillion foreign languages that are installed in MacOS X.
The author says it’s unsupported on 10.3, and he doesn’t plan to continue it. However, other people on the forums say they’ve had no troubles with it. I ran it on my G4 desktop and my PowerBook and had no troubles. I got back significant chunks of data: 1.2G and 1.3G respectively!