I try installing Safari 4.0.5 from the Apple website
Nope, not going to work. As stated above, 4.0.5 requires 10.5.8 - Software Update is only going to show the 10.5.8 update.Try it through Software Update.
I have to agree. Why not install 10.5.8?But there's no reason not to accept the 10.5.8 update as well...