Hi
You would need to extract Safari via the DVD Installer. Have a look at
this Apple article for installing other software, including Safari, from the Tiger DVD - see the section titled More custom reinstallation options with Mac OS X 10.4. While the article seems specific to Tiger, it also applies to Leopard.
Move to the trash the Safari.app found in your Applications Folder.
As a precaution, prior to reinstalling Safari, move your
Safari folder, found via the Finder in your Home Folder>Library to the Desktop. It has your bookmarks, history etc. Once the reinstall is completed, move the folder back to its original location writing over the newly created folder.
Install Safari per above. Once the install is complete, "Repair Permissions" via Disk Utility in your Utilities folder when you are finished.