I'm pretty sure that Xcode 2 and greater require 10.4. I have 10.3.9 and am using Xcode 1.5 which is the last before version 2. It still looks to be available on the
Developer Connection Member Site. After logging in, select "Developer Tools" in the "Downloads" frame at the right, then scroll about halfway down the page until you see "Xcode Tools v1.5" (372.4 MB).
You'll first need to install the 613.10 MB "Xcode Tools v1.2" which is right below it [EDIT: 1.2 not needed for 1.5, per below (thanks, gman)]