Due to recent malware that is floating around the Internet, this OSX
Security Update is strongly recommended. You may need to update to the
latest versions of Panther (10.3.9) or Tiger (10.4.5) before this
update can be applied:

http://docs.info.apple.com/article.html?artnum=303382

Use Software Update to actually install the update. The above link is
for information only.

Alex