By the settings I suggested above and set “Mac OS X 10.4u SDK” as SDK setting of the project, the product is built as universal binary which contains i386 code running on 10.4.x or later and PPC code running on 10.3.x or later.
Also, set “ppc i386” for architechture in the release build setting.
Since gcc3.3 is used for PPC version, the built product can run safety on Mac OS X 10.3.