Mac OS X 10.5.6 Update
The 10.5.6 Update is recommended for all users running Mac OS X Leopard and includes general operating system fixes that enhance the stability, compatibility and security of your Mac.
For detailed information on this update, please visit this website: http://support.apple.com/kb/HT3194
SHA 1 digest = 684f67524a92b4314a4bdd52498fb3b6af8f9ded
For explanation of what a SHA1 digest is, please visit this website: Mac OS X: How to verify a SHA-1 digest.
For detailed information on Security Updates, please visit this website: Apple security updates.