Yesterday Apple released Security Update 2008-005. This update fixes some long-standing major security holes in Leopard. It is highly recommended for all Mac OS X 10.5 Leopard users.
To update your computer, click on the Apple Menu (in the upper left corner of your screen) and choose Software Update. The update isn’t too large but DOES require a RESTART so set aside a few minutes for the download & installation when you run Software Update.
For more information on the update read this article from Apple: http://support.apple.com/kb/HT2647
