If you want to reinstall Safari, you need to do this:
1. Insert your Mac OS X 10.4 install/restore disc and navigate to the Optional Installs folder.
2. Open the Optional Installs.mpkg file, check the box in the list of applications to install just Safari, then run the Installer.
3. Quit the Installer when it's done, eject the disc, and you will have Safari 2.x.
4. Download and install the 10.4.11 Combo Update. This will give you Safari 3.0.4.
5. Download and install the Safari Update for Tiger. This will update Safari to 3.1.2.
6. Use Disk Utility to Repair Permissions.
Mulder